I have tested TV v12 on:
It all gives the same result (translated from Polish)
Partner is not connected to router
Error Code: WaitforConnectFailed
It is a pity that TV is not that much supported under Linux.
It works on win7 & 10 on the same hardware.
EDIT: Under mint with kernel 4.10.0-38 it worked once and now it is the same. Like something was updated and it stopped working.
I finally found the fix for my particular problem by logging in with XOrg vice Wayland.
I had to log off the session, select my username, then the gear shows up. Select Ubuntu XOrg, put in password and log back in. Re-attempted to connect to PC from my phone, and bam, it worked. There is some explination about why on askubuntu, but I just know it worked for me.
Getting the older version worked for me. Thanks so much.
I downgraded to version 11 and it's working fine for me now.
Here's the previous versions link: https://www.teamviewer.com/en/download/previous-versions/