RT-AX86U 388.1 (and 388.2 B1) DNS/Internet Connectivity issues - router is setup from scratch

[vStache]

I have been using Merlin Firmware for multiple years on RT-AX86U. I make use of a number of extensions such as JFFS, DNS Filter, VPN Director, etc. I moved to 388.1 when it was released in Dec 2022 and had random connectivity issues. I moved back to 386.7.2 which has no issues.

Recently, I acquired another RT-AX86U and set it up from scratch on Merlin 388.1 (not using JFFS or DNS Director) and have the same issues. It looks like DNS resolution fails.

I moved the router to the current stock firmware (without even resetting) and everything works (of course stock f/w doesn't support JFFS and DNS Director which I have not used on the new router yet).

I was hoping that 388.2 would fix these issues. But when I used 388.2 B1 on the router, same connectivity issues returned.

My DNS setup uses DoT and DNSSec. I tried using different DNS providers ranging from Google, Clean Browsing and Quad9. The issues are the same.

This DNS setup works on Merlin 386.7.2 and current stock firmware.

I even tried switching DoT and DNSSec off but the issues remain.

Any help or guidance is appreciated as I would like to move my main router to the latest versions in case there are security upgrades.

 

[bbunge]

I tested Merlin 388.2 beta 1 with no DNS issues. I do use DoT with DNSSEC but I use Cloudflare Security:
1.1.1.2 and 1.0.0.2 with TLS Hostname of security.cloudflare-dns.com
These have to be manually entered but do work. I have had "issues" with Quad9 and other upstream providers as my ISP seems to route their anycast addresses to data centers across the country from me.

 

[vStache]

Figured the issue out.

I use the router's OpenVPN to connect to a VPN provider and I have been setting the VPN Client DNS option to Strict. Changing that to Disabled seems to have fixed the issue.

I always use VPN Director and only a couple of devices were set to use the VPN and rest are set to use the WAN directly. But the VPN Client DNS setting seems to be affecting the entire network's DNS access.

With this change 388.1 seems to be working without issues as of now.

 

[vStache]

Updated our main router to 388.1 over the weekend with the VPN client DNS set to Disabled. No issues so far. It looks like I found the issue and workaround.

I might have found a bug in the firmware. Is there a way to report an issue such as this?

 

[L&LD]

You have already reported it.