WiFi is NOT a stable reliable transport medium, and it is even more likely to run into conflicts in urban environments. WiFi can work wonderfully for many use cases, but jitter/latency sensitive traffic can pose a challenge. As always, test using a wired Ethernet connection (with WiFi turned off on OBS Studio PC). If problem goes away, that answers your question. Unless you have real-time WiFi monitoring equipment, adequately testing WiFi throughput can be quite technically challenging (to be thorough and complete in analysis... ie, super easy to be misled).
I get that testing with Ethernet might not be simple for some folks. However, you have to ask yourself time vs money (if required to get USB to Ethernet adapter and cable, which are relatively cheap nowadays).
I'd also clean up your setup
- mismatched audio device sampling rates
- research the game,/window/display/capture considerations in same scene (I forget which are known problems)
- beware well known and commented on network issues caused by streamlelements (PoS s/w)
the above is to make sure those items/moisconfigs are contributing to issue
but your real issue is
20:07:33.410: Output 'simple_stream': Number of dropped frames due to insufficient bandwidth/connection stalls: 219 (44.3%)
You need to fix your LAN/WAN connection. period. highest probability is your WiFi link (and yes, was working fine for X period of time... including years.. and doesn't work now is NOT unexpected/unusual). Then follow FAQ in my .sig on connection issues, or other posts on this issue