RT-AX58U DNS-over-TLS (DoT) issue with Guest Networks

[icodehead]

I ran into an issue with the RT-AX58U (ASUSWRT 3.0.0.4.386_45898, No AiMesh) router using DNS-over-TLS (DoT Strick or Opportunistic) running over any Guest Network (Guest 2 is set to ap_isolate=0).
I am using Google TV and Sony Bravia TV devices. When starting a video from Hulu or HBOMax, the app freezes or returns an error but videos all work fine from the main wireless. I have tried several DNS DoT services without success. Other apps all work fine like Netflix, Amazon Prime, Apple TV, Philo, Peacock, Youtube, PBS, etc.
Because of this issue and the Crashlogs I am getting (about one a week, which ASUS has yet to fix), I am ready to throw in the towel. I love ASUS routers but since June 2021 I have been debugging issues both with ASUSWRT and Merlin (Crashes on Merlin are even worst).
Has anyone experienced anything like this or know something else this could be?
Whats the most stable ASUS router with DNS-over-TLS you would recommend getting?
Any help is greatly appreciated.

 

[bbunge]

Per chance did you change the default LAN IP Address?

 

[icodehead]

Per chance did you change the default LAN IP Address?

Yes. Changed to 192.168.xx.1 but why would that matter?

 

[bbunge]

Yes. Changed to 192.168.xx.1 but why would that matter?

It is the way the router handles DNS on the guest WIFI. While I can not point to anything specific, changing the LAN IP address could cause problems with the Guest.

My recommendations (This is a test to see if it will help):

Use Asus firmware.

Hard Factory reset. See: https://www.asus.com/support/FAQ/1039078

Configure manually. Do not use saved settings! Use Dual Band SmartConnect. SSID and passphrase alpha numeric with no special characters or spaces. Upper case letters OK. 2.4 GHz set to 20 MHZ Auto Channel, 5 GHz set to 80 MHz Auto Channel. WPA2-Personal. Use WIFI6. Do not change any other WIFI settings. Do not change router IP address. OK to change DHCP Pool of addresses and manually assign addresses. Use AiProtect and set QOS, Adaptive, if needed. Set up Guest WIFI with WPA2-Personal. Start with first guest which will give the clients a different LAN address from the router.

Sounds extreme but give it a try. Might just work!

 

[icodehead]

Thanks for the suggestions. I will work on this after I'm done working with ASUS T2 support over crashing problems. I have since gone back to unsecured DNS using cloudflare and can live with this a short time. I'd rather get the router stable first.
Also, I discovered that everything works fine if the Google TV Chromecast or Sony Bravia TV are connected to the 2.4G eth5 main wireless network!