After first install of iOS App, SignalR (Websockets, long polling) is failing

Hey,

me and my team had a bug, that each time after we freshly installed our cordova iOS App, our server connection (using SignalR, logn polling) was failing with 400 Bad Request.
Stopping, starting, reestablishing of this connection didn't help, but closing and reopening the App did.

We had a really tough time to locate this bug to this plugin. (same behaviour with cordova-plugin-wkwebview-engine). We are now using the default UIWebview and everything works fine.

Any clue why this is happening? Maybe there is some startup proble with the webserver code?
Would be great if we can use this plugin since the UIWebview is slow and buggy on it's own way.