Discord voice is not working on home network

Beilish · October 29, 2022

Hello everyone, trying to help a friend remotely, but wasn't able to find a solution.

Issue:

When he opens Discord and tries to make a voice call, it says "routing" and then "rtc connecting", but eventually it gives up and says "no route".
Same happens on his phone when connected to the Wifi. When using LTE it works, so we I guess it's nothing local on his PC/phone.

What we tried:

Clearing DNS cache
Manually setting the DNS server on his adapter to 8.8.8.8.
Changing the DNS in his router to 8.8.8.8 instead of his ISP's IP.
Various winsock commands.

The weird thing is, when I use his ISP's DNS to resolve discord.gg, I get:

~ dig @213.57.2.5 discord.gg

; <<>> DiG 9.16.1-Ubuntu <<>> @213.57.2.5 discord.gg
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 45925
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
; COOKIE: 9589d57594f7572e8bdedfc3635d0e2fe7d58c339348d18e (good)
;; QUESTION SECTION:
;discord.gg.                    IN      A

;; Query time: 6 msec
;; SERVER: 213.57.2.5#53(213.57.2.5)
;; WHEN: Sat Oct 29 14:25:23 IDT 2022
;; MSG SIZE  rcvd: 67

➜  ~

When I try the same with 8.8.8.8 it works:

➜  ~ dig @8.8.8.8 discord.gg

; <<>> DiG 9.16.1-Ubuntu <<>> @8.8.8.8 discord.gg
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34451
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;discord.gg.                    IN      A

;; ANSWER SECTION:
discord.gg.             300     IN      A       162.159.134.234
discord.gg.             300     IN      A       162.159.136.234
discord.gg.             300     IN      A       162.159.133.234
discord.gg.             300     IN      A       162.159.130.234
discord.gg.             300     IN      A       162.159.135.234

;; Query time: 59 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Oct 29 14:25:59 IDT 2022
;; MSG SIZE  rcvd: 119

➜  ~

The weird thing is, even when we manually set the router's DNS to be 8.8.8.8, it still didn't work. We tested both his PC and phone. What am I missing?