This is an unlinked Dropbox on Mac Sonoma 14.5

You cannot quite see, but there have been for a while, and unlike on my desktop machine with the exact same OS and DB install versions, NO sync symbols to the right of files or folders (green checkbox or blue spinning circle).  The dropdown control panel, pictured, shows "Your files are up to date".  My sync settings and screen showing the DB version are below that.   Indeed, new files added to the synced folders on other computers do show up now.  Yesterday they did not, but after a new clean reinstall at noon today they do.  Tis morning I could access no files on the on-line-only-sync'd laptop due to that server/network error message reported above.  Now I can.    

In short, performance has been spotty to non-existent on both machines.  Neither machine has any odd configuration or integration as the DB folders are in the default locations in the Library/CloudStorage folder (with aliases--business and personal DBs--appearing in the user folder).  I would note that on the desktop just now my primarily DB Team folder also has no sync symbol, but the other three DB folders do have this.  

One other thing I notice is that the desktop with the exact same DB install (215.4.7202) on both machines show up differently in finder.  On the desktop in a finder window there is a dropbox symbol and drop down action list, while this does not appear on the laptop (both pictured below, laptop first).  I have restarted numerous times and stopped all other extensions from loading, leaving only Dropbox.  But this icon does not appear on the laptop.  On the desktop, the dropbox icon is to the right of the action button. 

Oh, and by the way, I spent two days with the support team a month ago and got nowhere.  I ran out of patience trying every possible version of DB.  

I had tried to place my DB folders on an external drive in my desktop and perhaps this was the problem.  I'd done it before with a Windows 10 machine and it's been working.  I ended up buying a 6TB drive for my desktop and setting that up as the boot drive for the desktop.  Maybe this resolved the problems there.  However this took a month to set up with all the data I had to transfer over and then synchronize, aka resynchronize.  

Hey Chatterbox, I'm glad that after the reinstall, your files are now syncing again.

Regarding the difference between the two computers, is it possible that one of them is using the Dropbox for macOS on File Provider version of Dropbox and the other one is not?

On the File Provider version, the Dropbox folder would be located in ~/Library/CloudStorage, while on the older version the Dropbox folder would be in Locations.

Not sure about the version and status of Dropbox. Photo below.