ANSWER: Disable IPV6 from the PC wireless adapters:
Start-> Control Panel -> Network and Sharing Center -> Change Adapter settings -> right-click on network adapter, select Properties -> uncheck IPv6 checkbox -> click OK.
TeamViewer has been working great for me for a long time, but 2 days ago, I started receiving the error message "A connection could not be established. Partner could not be contacted at the given network address." Sometimes, I also receive the error "No connection to partner! Partner did not connect to router. Error Code: WaitforConnectFailed"
I will try to list as much about my network setup as possible:
1 PC running Windows 7 64-bit
1 PC running Windows 10 64-bit
1 Samsung Smart TV (Connected via wifi)
Xfinity Router with 2 running wifi networks (2.4GHz and 5.0GHz) I am connected to the 5.0GHz network
Avast Premier Antivirus running on both PCs
I have uninstalled and reinstalled TeamViewer on both PCs. After rebooting my router, TeamViewer works for a split second and then stops again. I have selected the option for Windows logon to "Allow for all users." I have added the Teamviewer.exe as an exclusion in my antivirus software on both PCs.
Even weirder is that on the PC running Windows 7, I'm able to access only one of my partner computers. From the Windows 10 PC, I'm unable to access any partner PCs.