Where am I being throttled/rate limited in elastic beanstalk app with dotnet core?

Question

I have an elastic beanstalk dotnet core application with settings close to default. In my code I listen on a websocket. I have noticed that whenever the client begins writing to the websocket quickly (more than say 5 times per second) it gets disconnected.

It seems likely that this is due to some sort of rate limiting or throttling, but for the life of me I can't figure out where this is happening.

Elastic beanstalk doesn't seem to be doing anything by default. Dotnet core's default settings seem to restrict only the max buffer size which is very large.

Any ideas on where to look? I have been banging my head against this for a while.