I have been using TeamViewer since 2020.  In the beginning we got this message intermittently.  Then our internet provider contacted TV and determined it was a router (or something like that) on TV end that wasn't working.  TV gave them a work around.
It's been fine ever since. Now all of a sudden we are getting this message again.  I have tried all the trouble shooting steps from TV and awaiting a response to a ticket.  
Has anyone else gotten this message? and what worked for you to fix it?