[sorry, not in the mood for foolishness/ignorance today]
Folks - OBS isn't the problem. by definition, can't be. period. Even if OBS traffic is the apparent cause, OBS still isn't the problem. really
Does your network buckle under sustained upload traffic? appears so. In which case - fix your network!
Is the problem appearing only with OBS? still a network problem. Have you troubleshooted by streaming using another app with same output settings? No, then PEBKAC and any conclusions you've come to are likely faulty
Seriously, if whole house is impacted, not just OBS PC... then problem isn't on OBS PC (may be coming from it, but separate discussion)
OBS traffic isn't malicious. A true Crashed network means either
1. a bad network
2. traffic from a given device causing network crash (refer back to #1, though some malicious traffic combined with defective (piss poor quality, i.e. ALL consumer) network gear can cause a crash as well). This would include things like bad Killer Networks drivers which were reported to be causing issues at one time [but only impacted associated PC, not entire LAN].
Now, I consider settings on the network, which don't work with actual traffic to be in case#1. In which case, it is either piss-poor firmware or PEBKAC or both
There are the really odd ball cases where a bad NIC or cable creates scenario where invalid Ethernet traffic gets on the network, and then who knows what might happen depending on the exact packets, but that shouldn't be driven by a particular app. ie - similar upstream traffic load should result in similar problems (ie stream from another app, and is there a difference)
But in far more cases, a setting on a consumer router causes the router CPU to spike. and traffic flow slows or halts. With real-time, device monitoring this would be obvious, but on consumer devices I've only seen this on 3rd party firmware. So what appears to be a 'crash' is more often a 'hang'... but really depends on make/model/firmware of a given switch, and well outside OBS support considerations.
Then again, for more common is folks simply being unaware of how a home network works, and doing things, especially with WiFi, that is bound to cause problems, and then not recognizing the network traffic symptoms when they happen