Solved RT-AX86U Alpha3 - Internet Connection Issue

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I_wanna_go_fast

New Around Here
After installing the RT-AX86U Alpha 3 build (released earlier today) onto my router, internet no longer works on connected devices.

I tried to connecting to the router via wifi from my iPhone and my MacBook, both are unable to access any internet pages. When I try to ping an URL on a connected device, I get an "Unknown host" error. However when I ping an IP address directly, I get a response just fine.

-I tied setting the DNS address manually, that did not resolve the issue.
-I tried restoring router to factory settings, that did not resolve the issue.
-When I restore the firmware back to stock from Merlin, internet starts working just fine on devices.
-I'm able to ping a website URL from the Merlin interface just fine

I've attached the routers logs along with some screenshots for help.

Build Used: RT-AX86U_386.1_alpha3-g874b3ed69d
 

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dave14305

Part of the Furniture
dnsmasq is pointing to itself. Set a proper dns in WAN DNS.
Code:
Nov 14 12:13:07 dnsmasq[3355]: using nameserver 192.168.1.1#53
Nevermind, I see this is a double nat setup behind another router?
 

dave14305

Part of the Furniture
This router is setup behind my modem (which also acts as a router). Hence my modem IP is 192.168.1.1, and RT-AX86U router IP is 192.168.50.1.

On it! Give me 5 minutes to flash it back to Alpha 3!
Besides ping, also run dig www.Google.com or nslookup www.Google.com
 

I_wanna_go_fast

New Around Here
Besides ping, also run dig www.Google.com or nslookup www.Google.com

Done...

Code:
[email protected] ~ % ping http://www.Google.com
ping: cannot resolve http://www.Google.com: Unknown host

Code:
[email protected] ~ % dig www.Google.com      

; <<>> DiG 9.10.6 <<>> www.Google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 5403
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.Google.com.            IN    A

;; ANSWER SECTION:
www.Google.com.        189    IN    A    172.217.175.100

;; Query time: 92 msec
;; SERVER: 240d:1a:b11:1b00:6ed2:baff:fe1a:13f8#53(240d:1a:b11:1b00:6ed2:baff:fe1a:13f8)
;; WHEN: Sat Nov 14 22:07:58 JST 2020
;; MSG SIZE  rcvd: 48

Code:
[email protected] ~ % nslookup www.Google.com
Server:        240d:1a:b11:1b00:6ed2:baff:fe1a:13f8
Address:    240d:1a:b11:1b00:6ed2:baff:fe1a:13f8#53

Non-authoritative answer:
Name:    www.Google.com
Address: 172.217.175.100

[email protected] ~ %
 
Last edited:

dave14305

Part of the Furniture
Is IPv6 enabled on the ax86u? What if you disable it?
 

dave14305

Part of the Furniture
IPv6 is disabled.
I just tried enabling it as "native" to see if it would resolve the issue but same issue persisted. After disabling IPv6 again, issue still persists.
Ok, I’m not familiar with MacOS enough to know why it’s using an IPv6 dns server (240d:1a:b11:1b00:6ed2:baff:fe1a:13f8).
 

Mutzli

Very Senior Member
What is your WAN MTU set at? should be 1500:
1605360832954.png


In the older firmware this was set on by default to 1500
 

I_wanna_go_fast

New Around Here
What is your WAN MTU set at? should be 1500:

In the older firmware this was set on by default to 1500
It was blank. I actually set it to 1500 and it fixed the issue!
I wonder if the field went blank after flashing Merlin firmware. I'll do some more testing to see if this field actually gets cleared out after changing to Merlin.

So my original issue of no internet is fixed, but not sure yet if we have a bug here. Will report back tomorrow.


Ok, I’m not familiar with MacOS enough to know why it’s using an IPv6 dns server (240d:1a:b11:1b00:6ed2:baff:fe1a:13f8).
I think it was being cached somehow. If I use a website I've never visited before, then IPv6 does not appear.
 

I_wanna_go_fast

New Around Here
Actually, let's mark this as resolved! I'll update my other thread with my findings on the blank "WAN MTU" issue.

 

Mutzli

Very Senior Member
It was blank. I actually set it to 1500 and it fixed the issue!
I wonder if the field went blank after flashing Merlin firmware. I'll do some more testing to see if this field actually gets cleared out after changing to Merlin.

So my original issue of no internet is fixed, but not sure yet if we have a bug here. Will report back tomorrow.
It is a problem in this new firmware from Merlin. Must be the MTU default value that is not set. Others reported the same issue in the alpha thread last week and I experienced it as well on my end.
 

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