Quick update on latest troubleshooting steps tried:
- Bound Cells to internal network IP address as well as localhost 127.0.0.1 - no improvement
- Enabled Websockets in IIS (via Server Manager) - you might think that would be the obvious easy fix! Nope
- Added reverse proxy rewrite rule for outbound, only inbound was configured. No dice
- Enabled ARR via IIS Install Application Request Routing | Microsoft Docs
Not yet tried (or sure is relevant) IIS and Url-Rewrite: rewriting the outbound response contents - Microsoft Tech Community
I can see no reason our firewall would be blocking any connections as it appears to have a general rule to allow client server traffic through and no logs indicate any connection blocking…
Frankly I am still a bit confounded as to how everything appears to be working but this message still shows up and why the message says “…please make sure the server is up…”, if server was down there would be no website, error message or anything!!
TBC…