Thanks Aaron. Though for all, beware mis-interpreting the results of a SpeedTest. Such test are highly optimistic, vs the metrics important to livestreaming, which is the lowest sustained upload threshold (as well as jitter). So a SpeedTest is a good starting reference point (I use that test as well), but the upload results rarely (almost never) mean the rate you can stream at. And results can vary over time
Personally, I'd start with logging onto the router and seeing overall WAN traffic levels (primarily outbound/upload). And I'd have this available during service. Then again, if issue persists across multiple platforms, even when almost no one is around, then I'd start make sure some network devices/computers not using unexpected network traffic, and that includes the OBS PC. This includes making sure 'neighbors' aren't unexpectedly using Guest WiFi?
log shows Ethernet connected OBS PC. But you mentioned WiFi... is your Internet connection wired part of the way, then using something like a WiFi bridge? in which case you could have WiFi contention/interference issues