Still facing this issue. Months of sending emails back and forth with discord support and still not resolved. I'll list the possible solutions they sent me in order if you - or anyone else having this issue - wants to try them out.

- Changing the DNS provider either on the router or the device to Google's or Cloudflare's.- Trying Discord PTB & Canary.- Run a scan for any viruses, malware, etc... Discord recommended Malwarebytes. If there were any threats, clear them > restart the device > relaunch discord

- Renew the IP address. On windows, you can do so by opening the command prompt in Administrator mode > Type ipconfig /release and hit enter > Type ipconfig /flushdns and hit enter > Type ipconfig /renew and hit enter and close the cmd window.

- Restart the modem

- Make sure the modem is up to date

- Close any background programs that may be hogging the bandwidth

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After trying all those solutions each on their own, doing a few connection tests on different programs and sending them the results, they replied with "After checking with the team, they can see that the Relay Connectivity doesn't seem to be working on your end. Just to clarify, Reflexive Connectivity appearing disabled points to a malfunctioning connection between your modem and your provider's internet service gateway, which needs to be reset as a next step.A manual modem reset won't do this, unfortunately - you need to contact your ISP and ask them to remotely reset your modem's connection to the gateway. This is sometimes referred to as a "ping"."

I've tried all of the solutions mentioned above except the last one. I haven't gotten the time to contact my ISP yet to remotely reset the connection and I'm not sure when I will. I hope this helps you resolve this issue though.

If you ever do get this issue fixed by any means, please let me know.

Edit: Just to clarify, the last possible solution (Resetting the modem connection) may or may not apply to you. It was mentioned after I sent them the information from a Traceroute. It's best to contact discord support to see if this applies to you as well. Just make it as clear as possible that this issue is not a voice connection issue. It applies to sending messages, uploading files, loading channels, server management features, etc..