At OpDemand we're using WebSockets successfully through multiple ELBs. The trick is setting the listener to use TCP instead of HTTP. With TCP forwarding you l

At OpDemand we're using WebSockets successfully through multiple ELBs. The trick is setting the listener to use TCP instead of HTTP. With TCP forwarding you lose X-Forwarded-For headers, Cookie stickiness and a few other HTTP-specific features.. but you can always spin up a separate listener for that.