There are a lot of suggestions and solutions about what is fixing crashes on PC, but this is what did it for me.
I disabled UPNP on my router, and manually forwarded the ports from this article:
https://portforward.com/halo-infinite/
I never would have thought this would be the solution, and accidentally stumbled upon it trying to fix other network errors.
Anyways, if you’ve exhausted your options on crashing - give this a try.