Hello Richard,
I'd be curious if Chrome or Edge works with Web Client for you.
I've heard of this type of behavior with different browsers and as of yet, don't have a definitive resolution.
The closest I've been able to re-create this issue is in Chrome, where Web Client allowed me to login and it hung on the 'Microsoft Dynamics GP' screen that you mentioned and doesn't move past that. In my case, I saw this in IE as well.
I went into Internet Options in IE, added the URL as a Trusted Site and confirmed under ‘Trusted Sites’ that ‘Automatic logon with current user name and password’ was marked.
Still in Internet Options in IE, under Browsing History, I deleted the temporary files and verified that ‘Every time I visit the webpage’ option was marked, so nothing was being cached.
Once I did that, Web Client worked fine in IE.
Based on that, I went into Internet Options in Control Panel, and did the same, for Edge and Chrome, and that resolved the same issue there also.
Other than that, we haven't seen the volume (as of yet) to suggest Web Client has issues with Edge or Chrome or any other browser. I haven't done much testing with FireFox if any, so I don't have any further info specific to FireFox.
I'd try the above and see if that works for you as it did for me.
Thanks,
