Is it ok using local LAN names such as pi04.local?
yes that works indeed.
Thanks for sharing, but it's unrelated to my issue. I already connect using DNS name.
Interesting. I've just been testing some new front-end code for uibuilder on Mac (latest) and web sockets do seem to be working. However, I am using a secured link (HTTPS/WSS) which was alluded to in the shared thread.
Why anyone uses Safari is beyond me, it is the IE of the 2020's. It ignores new standards, sometimes forever, sometimes for years. All-round, a pain.
Thankfully, you can, these days, use sensible browsers like Vivaldi or not so sensible ones like Firefox on iOS and Mac. 
BTW, the new additions to the uibuilder client library are cross-browser stack-traces. Work great on Chromium and Firefox browsers but virtually useless on Safari as it does not provide much in the way of useful info. Sadly, while stack trace standards are currently making their way into the JavaScript standards, the output formats are still being left up to the browser which is a pain because the different engines use different formats.
You said in the first post that it hangs on startup .with the disconnected image'. Do you mean the 'Connection Lost Attempting to reconnect to server' popup? If so, with the original s/w, if you leave it 5 minutes (or a little more) does it recover?
