Close Altium before trying each of these three things (it's almost always the third one):
Check that the System time zone, date, and time are set correctly for both the server and client.
Turn off Bluetooth connectivity if the client is so equipped to rule out a driver conflict.
Deactivate extra network connections (cards, wireless & virtual)
Control Panel (View by set to: Category view) ► Network and Internet ► View Network status and tasks ► Change adapter settings
Control Panel (View by set to Large or Small icons) ► Network and Sharing Center ► Change adapter settings
Right-click to disable (or use "Disable this network device") for each connection that is not currently required
If the third recommendation resolves the issue, you can try enabling devices one at a time. The issue is caused by the number of devices rather than any particular one. For Altium Infrastructure Server (AIS) this issue has been resolved with the release of version 126.96.36.199, but you probably don't need all of those network adapter devices to be enabled anyway.