I had the same problem and i solved it. After I did everything from open ports to disable firewall, uninstall, instal etc. As the message say "check your connection". So I did.. but first i checked the speed, it was ok 80Mb/s UP , 90Mb/s Down so I thought there is no problem.. but after that I sed to me search deeper in the connection. I installed whireshark and I found some TCP low performance problems on TeamViewer ports. I stoped my LAN connection I made a hotspot wit my phone 14Mb/s and it worked.. Redi to connect and I got the ID and Pasword instantly :D. I changed my DNS server on my LAN conection and now it works fine on LAN. So make shore you have a GOOD internet connection . Good luck!
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