User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:108.0) Gecko/20100101 Firefox/108.0

Steps to reproduce:

1. Prepare a SOCKS5 proxy server

2. Open about:preferences in the browser and click "Network Settings"

3. Fill in "Manual proxy configuration", "SOCKS Host", "Port"

4. Select "Proxy DNS when using SOCKS v5"

5. Open a webrtc test page, for example https://ip.voidsec.com/

Actual results:

The "Web RTC:" item on the page, the relevant information is empty

Expected results:

The "Web RTC:" item on the page displays the address information of webrtc

The Bugbug bot thinks this bug should belong to the 'Core::Networking' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Randell, could you take a look at this one?

I wonder if it's a limitation of wanting to use UDP for WebRTC, but not being capable of doing that over SOCKS5 possibly as a result of the lack of implementation.

It's definitely not a global setting problem breaking everything at least.
I use containers, and the ones with a proxy specified can't use WebRTC while the functionality remains working outside of those containers.

Yes, I think WebRTC proxying doesn't work when a proxy is in use.
The SOCKSIOLayer does not have a method for sendto and recvfrom, so presumably it can't proxy UDP traffic.
This limitation is also present in (Chrome's SOCKS implementation](https://chromium.googlesource.com/chromium/src/+/HEAD/net/docs/proxy.md#socksv5-proxy-scheme).