Sync not connecting -- router settings?

I have experienced a sync error persistently in a new install of Endnote20 on Windows 11.
Error message is: “Endnote could not connect to the online sync service.”

I have been in touch with Endnote/Clarivate tech support but have not resolved this problem yet.

I was told to run a traceroute on my network router to make sure Endnote was able to connect to This resulted a timeout, whether behind my VPN or not. I assume the problem is with the router but I am not sure how to change settings to avoid this (if the router is blocking the connection).

Are there any special router settings or permissions that others have needed to employ to get sync functionality to work properly?

Thanks for your help,

Uninstall and re-install (several times)
I have also logged into and out of the online account to make sure it works.
I have also also followed several sets of instructions about removing libraries, emptying trash (desktop and in the cloud), but none of these things have resolved my sync error yet.