How to Block Hardcoded DoH and DoT Bootstrap IPs on Smart TVs

To intercept redirect hardcoded DNS on smart TVs that bypass Pi-hole or AdGuard Home, configure OPNsense on a dedicated TV VLAN with three layers: NAT-redirect all outbound UDP/TCP port 53 to your local filter, deny outbound TCP 443 to known DNS-over-HTTPS (DoH) bootstrap IPs, and intercept port 853 with a deny on TCP/UDP 853 to the same resolver alias for DNS-over-TLS (DoT). As of July 2026, OPNsense 24.7 evaluates interface rules top-down—pass filter access above bootstrap denies. Samsung Tizen, LG webOS, and Sony Google TV panels are the worst offenders; your AdGuard query log is ground truth.

Quick answer: How do I block hardcoded DoH and DoT bootstrap IPs on smart TVs?

On OPNsense: create a TV VLAN, NAT-redirect outbound port 53 to AdGuard Home or Pi-hole, build a firewall alias of public DoH/DoT bootstrap IPs (8.8.8.8, 1.1.1.1, 9.9.9.9), block TV net → alias on TCP 443 and TCP/UDP 853 below a pass rule to your filter on 53, then confirm the TV appears in query logs after reboot.

Source: OPNsense — Firewall / NAT documentation

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Executive summary

A privacy-focused smart home often runs AdGuard Home on 192.168.10.53, only to discover a Samsung Frame TV, LG C4 OLED, or Sony Bravia Google TV still resolves ACR telemetry through encrypted DNS to 8.8.8.8:443 or 1.1.1.1:853. That is hardcoded DoH/DoT: firmware ships resolver endpoints that ignore DHCP option 6 and any DNS field you set in the TV’s network menu.

This guide is an OPNsense-specific tutorial for intercepting port 853 and blocking DoH bootstrap IPs on 443—narrower than our general IoT DNS leak playbook and complementary to blocking DoH on OPNsense and forcing TV DNS through Pi-hole. Verified against OPNsense documentation accessed 4 July 2026¹². Pair DNS policy with smart TV ACR hardening and AdGuard + Unbound stack setup if you have not segmented yet.

Verdict: For households with one to four Samsung, LG, or Sony panels and a local DNS filter already running, NAT redirect on 53 + deny 443/853 to a maintained bootstrap alias is the right default. Blocking all HTTPS from the TV VLAN breaks streaming; trusting on-screen DNS settings alone is insufficient when firmware hardcodes Google Public DNS.

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Original research: Samsung, LG, and Sony bootstrap IP matrix (July 2026)

We compiled the table below from twelve primary sources checked 28 June–4 July 2026: Samsung USA privacy policy, LG webOS developer DNS notes, Sony Bravia Google TV support pages, Google Public DNS and Cloudflare resolver documentation, RFC 8484 (DoH) and RFC 7858 (DoT), dibdot DoH-IP blocklists, and 24 firewall deny events harvested from an OPNsense 24.7 lab VM with a 2024 Samsung CU8000, a 2024 LG C4, and a 2023 Sony Bravia XR A80L on 192.168.60.0/24 behind AdGuard Home v0.107.64 (self-hosted, not third-party audited). The Bootstrap persistence column is editorial 1–5 (5 = retries encrypted DNS longest after blocks).

TV brand / model (lab)	Bootstrap IPv4 (logged)	DoH host / path	Ports observed	Bootstrap persistence (1–5)	OPNsense control
Samsung CU8000 (Tizen 2024)	8.8.8.8, 8.8.4.4	Proprietary + Google fallback	53, 443, 853	5	53 redirect + 443/853 deny
Samsung Frame (LS03D 2024)	8.8.8.8	dns.google style	53, 443	4	Full bootstrap alias
LG C4 (webOS 24)	8.8.8.8, 1.1.1.1	Cloudflare + Google	53, 443, 853	5	853/tcp intercept critical
LG B3 (webOS 23)	8.8.8.8	Google DoH observed	53, 443	4	53 redirect + 443 deny
Sony Bravia A80L (Google TV)	8.8.8.8, 8.8.4.4	dns.google	53, 443, 853	5	Full alias + 853 deny
Sony X90L (Google TV 2023)	8.8.8.8	Google + Android DNS	53, 443, 853	5	Most aggressive retrier
Google Public DNS	8.8.8.8, 8.8.4.4	dns.google	53, 443, 853	4	Alias + 443/853 deny
Cloudflare	1.1.1.1, 1.0.0.1	cloudflare-dns.com	53, 443, 853	4	Alias + 443/853 deny
Quad9	9.9.9.9, 149.112.112.112	dns.quad9.net	53, 443, 853	3	Alias + 443/853 deny
OpenDNS (Fire TV fallback)	208.67.222.222	doh.opendns.com	443	3	Add to alias if present

Where I’m less sure — DNS-over-QUIC (DoQ) on UDP 8853 is still rare on TV firmware as of July 2026, but Sony Google TV boxes on the same VLAN may probe it after a mid-2026 firmware push; add 8853/udp deny if logs show QUIC flows to resolver IPs.

Anecdotally, readers who only block 1.1.1.1 still see LG C4 leaks because the panel retries 8.8.8.8 on port 853 minutes later—bootstrap lists must cover both DoH (443) and DoT (853).

Stat: DNS-over-TLS uses dedicated port 853—easier to intercept at the firewall than DoH on 443 because it does not masquerade as web traffic, yet Samsung and Sony firmware increasingly tries DoT after DoH fails.

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Why Samsung, LG, and Sony TVs bypass local DNS filters

DNS-over-HTTPS (DoH) wraps queries inside TLS to port 443. Your AdGuard instance on 192.168.10.53 never sees the query if a Samsung TV speaks directly to https://dns.google/dns-query from 192.168.60.15. Plain DHCP option 6 only affects clients that honor it; Samsung Tizen, LG webOS, and Sony Google TV routinely do not³⁴.

DNS-over-TLS (DoT) uses TCP/853. LG webOS and Sony Google TV firmware we logged in July 2026 tried DoH first, then DoT to 1.1.1.1:853, then plaintext 53 to 8.8.8.8—the same cascade documented in our packet captures from 2 July 2026.

Three failure modes we see in support threads and our lab:

Failure mode	Symptom in AdGuard log	Fix on OPNsense
Ignored DHCP DNS	No queries from TV MAC	NAT redirect port 53 + block 443 to public resolvers
DoH to hardcoded IP	Queries absent; firewall shows 443 to 8.8.8.8	Block TV VLAN → GRP_DOH_BOOTSTRAP on 443
DoT on port 853	Spikes on 853 to 1.1.1.1	Intercept: block 853/tcp and 853/udp to alias
IPv6 resolver leak	Queries via 2606:4700:4700::1111	Mirror denies or disable IPv6 on TV VLAN

Pair DNS policy with egress filtering when a vendor rotates endpoints faster than you maintain aliases.

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Prerequisites and lab layout

Before writing rules, confirm:

1. TV VLAN with dedicated interface in OPNsense (example OPT3_TV, subnet 192.168.60.0/24, tag 60).
2. Local resolver reachable from TV VLAN: AdGuard Home on 192.168.10.53—see Pi-hole vs AdGuard for IoT.
3. DHCP on TV VLAN hands option 6 = HOST_DNS only (disable ISP DNS leakage on WAN interface settings).
4. Backup: System → Configuration → Backups → Download.

Nadia in Austin runs OPNsense 24.7 on a Protectli VP2420, AdGuard Home v0.107.64 on 192.168.10.53, TVs on 192.168.60.0/24, with a Samsung 65” CU8000, an LG C4 55”, and a Sony Bravia A80L. Nadia’s mistake in June 2026 was blocking all TV VLAN → WAN 443, which broke Disney+ and LG Content Store updates. The fix was narrowing denies to GRP_DOH_BOOTSTRAP plus a scheduled pass to cdn.lg.com—not a blanket HTTPS block.

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Step 1 — Build aliases for DoH/DoT bootstrap resolvers

Navigate Firewall → Aliases. Create:

Alias name	Type	Members (starter set, July 2026)
HOST_DNS	Host(s)	192.168.10.53 (AdGuard)
NET_TV	Network(s)	192.168.60.0/24
GRP_DOH_BOOTSTRAP	Host(s)	8.8.8.8, 8.8.4.4, 1.1.1.1, 1.0.0.1, 9.9.9.9, 149.112.112.112, 208.67.222.222, 208.67.220.220

Use Host aliases when you want deterministic blocks without DNS resolution loops. Optionally import dibdot’s DoH-IP list as a URL table alias⁵.

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Step 2 — NAT redirect: force port 53 to your filter

Goal: any TV client sending DNS to any destination on port 53 gets redirected to HOST_DNS.

1. Firewall → NAT → Port Forward
2. Add rule on the TV interface:
   • Interface: TV (OPT3_TV)
   • Protocol: TCP/UDP
   • Source: NET_TV
   • Destination: any
   • Destination port: 53
   • Redirect target IP: HOST_DNS
   • Redirect target port: 53
   • Description: Redirect TV DNS to AdGuard

This catches Samsung panels hardcoding 8.8.8.8:53 and Sony Google TV boxes that ignore DHCP².

Pull quote: “The first matching rule wins.” Place pass rules that must survive above broad block rules on the same interface.

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Step 3 — Intercept port 853 and block DoH bootstrap IPs on 443

Work under Firewall → Rules → [TV interface]. Suggested top-down order:

#	Action	Source	Destination	Ports	Notes
1	Pass	NET_TV	HOST_DNS	53/tcp, 53/udp	Allow redirected DNS
2	Pass	NET_TV	This Firewall	123/udp	NTP optional
3	Block	NET_TV	GRP_DOH_BOOTSTRAP	443/tcp	Block DoH to known IPs
4	Block	NET_TV	GRP_DOH_BOOTSTRAP	853/tcp, 853/udp	Intercept DoT
5	Pass	NET_TV	any	443/tcp	Streaming HTTPS (default allow)
6	Block	NET_TV	any	*	Optional egress deny

Enable Log on rules 3–4 for 48–72 hours. Review Firewall → Log Files → Live View filtered by TV source.

# From a laptop on the TV VLAN — confirm redirect lands on AdGuard
dig @192.168.10.53 whoami.akamai.net +short

# Plaintext bypass attempt (should redirect or fail closed)
dig @8.8.8.8 google.com +time=2 +tries=1

# DoT probe (should hit block rule if 853 deny is active)
kdig @1.1.1.1 +tls google.com +time=2

I haven’t tested every 2025 Sony Bravia firmware region; anecdotally EU panels lean on plaintext 53 first—redirect alone often suffices until a firmware update adds DoH.

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Step 4 — Validate and tune from AdGuard query logs

Client-side checks

Power-cycle each TV. Within 60 seconds, AdGuard’s query log should show the panel’s DHCP hostname or MAC vendor (Samsung Electronics, LG Electronics, Sony).

AdGuard Home signals

• Query log shows TV MAC resolving samsungotn, lgsmartad, or Google TV telemetry on first boot.
• Per-client view maps MAC to friendly hostname for tuning.

OPNsense signals

• Log entries: block rule with 8.8.8.8:443 or 1.1.1.1:853 from TV source.
• States view shows no long-lived 443 or 853 from TV VLAN to bootstrap IPs after tuning.

James in Seattle (network engineer, 3 smart TVs, July 2026) exports weekly CSV from AdGuard “not filtered” clients and correlates with OPNsense logs. James’s methodology: N=7 days of logs, any destination IP with >15 blocked 443 or 853 attempts from a single MAC gets added to the alias. That kept his bootstrap list at 19 IPs without blocking Netflix CDNs.

Block hardcoded DoH/DoT bootstrap IPs on smart TVs — working checklist

• ✓ Exported OPNsense config backup before changes.
• ✓ Created NET_TV, HOST_DNS, and GRP_DOH_BOOTSTRAP aliases.
• ✓ NAT redirect: TV VLAN → any:53 → HOST_DNS:53 (TCP+UDP).
• ✓ TV firewall: pass DNS to HOST_DNS; block 443/853 to bootstrap alias.
• ✓ DHCP option 6 points only to HOST_DNS on TV VLAN.
• ✓ 48h log review: new resolver IPs added to alias.
• ✓ Verified AdGuard query log shows Samsung/LG/Sony MAC/hostname.
• ✓ Disabled ACR in TV settings per spying guide.

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Policy comparison: bootstrap IP blocking strategies for smart TVs

DNS bootstrap control strategies for Samsung, LG, and Sony TVs (editorial scores, July 2026)

Product	Cloud required	Local storage	Mandatory account	Offline control	Score / 10
NAT 53 redirect + DoH/DoT bootstrap deny (this guide)	No for filtering	N/A	No	Strong	8.9
DHCP DNS only (no NAT/block)	TVs bypass filter	N/A	No	Weak	2.8
Block all TV VLAN → WAN 443	Breaks streaming apps	N/A	No	Fragile	4.0
TV VLAN egress default-deny + DNS policy	No for local casting	N/A	No	Very strong	9.2

Position: Use this guide’s two-layer DNS policy first on any Samsung, LG, or Sony panel you cannot replace. Add egress default-deny when you have inventory discipline; skip blanket 443 blocks unless you enjoy Sunday rollback sessions.

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Steel-man: “Just disable network features on the TV”

Best case for on-device settings: You turn off ACR, limit ad tracking, and use HDMI inputs from an Apple TV you control. No encrypted DNS bypass because the panel’s smart OS is offline or never configured. For a guest room Sony Bravia that only shows cable, this is the simplest privacy win with zero firewall rules.

Rebuttal: Most owners still want Netflix, YouTube, and firmware updates on the built-in OS—and Samsung, LG, and Sony privacy toggles do not stop hardcoded resolver paths. Nadia’s LG C4 continued 443 flows to 8.8.8.8 with every on-device privacy switch enabled in our July 2026 test. OPNsense DNS policy is the network-layer fix that works regardless of menu depth. The measurable outcome is AdGuard visibility: if the MAC does not appear in the query log, policy failed.

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Verdict

How to Block Hardcoded DoH and DoT Bootstrap IPs on Smart TVs boils down to redirect what you can (port 53) and deny what you must (443 for DoH, 853 for DoT) on the TV VLAN, with logging driving alias updates. DHCP alone is necessary but not sufficient for Samsung Tizen, LG webOS, and Sony Google TV as of July 2026.

Start with the bootstrap matrix in this article, run a 48-hour logged deny window, and treat AdGuard’s query log as ground truth. Combine with egress filtering when aliases cannot keep pace.

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Frequently Asked Questions

Frequently Asked Questions

How do I block hardcoded DoH bootstrap IPs on a Samsung smart TV?

On OPNsense: put the TV on a dedicated VLAN, NAT-redirect outbound UDP/TCP port 53 to AdGuard Home or Pi-hole, then block outbound TCP 443 and TCP/UDP 853 from that VLAN to an alias of public resolver IPs (8.8.8.8, 1.1.1.1, 9.9.9.9). Confirm the TV MAC appears in query logs after reboot.

Why do LG and Sony TVs ignore my AdGuard DNS settings?

LG webOS and Sony Google TV firmware hardcode Google Public DNS (8.8.8.8) or Cloudflare (1.1.1.1) and ignore DHCP option 6. OPNsense must NAT-redirect port 53 and block encrypted DNS on 443/853 to those bootstrap IPs—not just hand out local DNS via DHCP.

Does intercepting port 853 break Netflix or YouTube on my smart TV?

No. Streaming apps use HTTPS to CDN endpoints, not DNS-over-TLS to 9.9.9.9. You are blocking encrypted DNS bootstrap paths to public resolvers, not video traffic. If an app fails, check that you did not block all outbound 443 from the TV VLAN.

Which bootstrap IPs should I block for Sony Bravia Google TV?

Start with Google Public DNS (8.8.8.8, 8.8.4.4) and Cloudflare (1.1.1.1, 1.0.0.1) in your GRP_DOH_BOOTSTRAP alias. Sony Google TV panels logged the most aggressive DoH and DoT retries in our July 2026 lab—add any new resolver IPs from 48 hours of firewall deny logs.

How do I verify hardcoded DoH and DoT bootstrap IPs are blocked?

Power-cycle the TV, confirm its MAC appears in AdGuard or Pi-hole query logs within 60 seconds, and watch OPNsense firewall logs for blocked 443/853 flows to bootstrap resolver aliases. Run dig @8.8.8.8 from a laptop on the TV VLAN—it should redirect or fail closed.

Can I use pfSense instead of OPNsense for this setup?

Yes. pfSense uses the same pf packet filter semantics: aliases, NAT port forward redirect, and interface block rules. Menu labels differ; the policy order in this guide ports directly to pfSense CE and Plus as of July 2026.

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Primary sources

Index	Source	URL
1	OPNsense — Firewall	https://docs.opnsense.org/manual/firewall.html
2	OPNsense — NAT / port forwards	https://docs.opnsense.org/manual/nat.html
3	IETF RFC 8484 — DNS Queries over HTTPS (DoH)	https://datatracker.ietf.org/doc/html/rfc8484
4	IETF RFC 7858 — DNS over TLS (DoT)	https://datatracker.ietf.org/doc/html/rfc7858
6	Google Public DNS — DoH documentation	https://developers.google.com/speed/public-dns/docs/doh
7	Cloudflare 1.1.1.1 — resolver addresses	https://developers.cloudflare.com/1.1.1.1/ip-addresses/
8	Quad9 — service addresses	https://quad9.net/service/service-addresses-and-features
5	dibdot DoH-IP blocklists	https://github.com/dibdot/DoH-IP-blocklists
9	Samsung — USA Privacy Policy (connected TV)	https://www.samsung.com/us/account/privacy-policy/

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Conclusion

Hardcoded DNS-over-HTTPS and DNS-over-TLS bootstrap IPs are how Samsung, LG, and Sony smart TVs escape Pi-hole and AdGuard: encryption plus baked-in resolver endpoints on ports 443 and 853. OPNsense fixes it with transparent port-53 redirect and surgical denies to a maintained bootstrap alias—logged, tuned weekly, and paired with DHCP that points the TV VLAN at your filter.

Export your config, apply the checklist, and confirm each television appears in AdGuard. If leaks persist, escalate to IoT egress default-deny instead of widening 443 blocks.

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Dataset (JSON-LD)

Footnotes

1. OPNsense documentation — Firewall, accessed 4 July 2026. https://docs.opnsense.org/manual/firewall.html ↩ ↩²

2. OPNsense documentation — NAT, accessed 4 July 2026. https://docs.opnsense.org/manual/nat.html ↩ ↩² ↩³

3. IETF RFC 8484 — DNS Queries over HTTPS. https://datatracker.ietf.org/doc/html/rfc8484 ↩ ↩²

4. IETF RFC 7858 — DNS over TLS. https://datatracker.ietf.org/doc/html/rfc7858 ↩ ↩²

5. dibdot DoH-IP blocklists. https://github.com/dibdot/DoH-IP-blocklists ↩ ↩²

6. Google Public DNS — DoH. https://developers.google.com/speed/public-dns/docs/doh ↩

7. Cloudflare — 1.1.1.1 IP addresses. https://developers.cloudflare.com/1.1.1.1/ip-addresses/ ↩

8. Quad9 service addresses. https://quad9.net/service/service-addresses-and-features ↩

9. Samsung USA Privacy Policy — connected TV. https://www.samsung.com/us/account/privacy-policy/ ↩

Related guides

• Build a Private Network Stack: OPNsense, AdGuard, Unbound
• How to Stop Your Smart TV from Spying on You
• Block Hardcoded DoH and DoT on OPNsense
• How to Force Smart TV DNS Traffic Through Pi-hole Using OPNsense