SignalR Falling Back to Long Polling vs Websockets
I have an issue with a SignalR application that works fine in our Dev environment but not in Production.
This application runs off Javascript and attempts to connect to a Windows 2012 R2 server (IIs 8.5, .net 4.5) with a Websockets connection.
In our Dev environment the Websockets connection works fine, but in Production it will fall back to Long Polling. Both servers have the exact same webconfig file.
We've pulled the Production Server out from behind our load balancer to verify there is no interference there and I've also verified that the VLAN the production server is on won't block any traffic
Websockets is definitely installed and enabled on the Production server, and the IE settings on both servers are exactly the same.
I run a very similar setup with no issues in our a Dev environment vs. Production with a load balancer.
You mention that your webconfig file is the same, but on the 2012 server have you verified that Web Sockets option is installed and enabled?
Had a similar problem (except worked in prod not dev). Even though the web.config was the same, I had to set <httpRuntime targetFramework="4.5.2" /> for websockets to work on both environments.