A specific Internet access connection type (Wifi, broadband etc.) has nothing to do with program's connectivity except only it's a very slow network. Usually, but not always, mobile Internet access is slower than other access types such as a regular ISP or a WiFi hotspot.
I am using 188.8.131.52 viewer and when trying to do any file transfers with remote computers, the file transfer window is MASSIVE. Now on my computer setup I have 2 4K monitors, one is horizontal, one is vertical, and a 1080p monitor as well. The window shows up spanning multiple monitors and much be resized to see the entire window so you can see buttons and such.
Does this happen each time you start a File Transfer mode session? I.e. it doesn't remember the size that you set.
Additionally, I have a very hard time navigating to directories, I constantly get errors, then after trying a few times it might work. Sometimes I have to just use Remote Utilities to initiate a VNC session so I can do file transfers it has gotten so bad.
This is a known issue, specifically the issue with slow folder browsing in File Transfer mode. Later this year we are going to significantly re-write the File Transfer module and will fix these issues, and also add a couple of useful features.
The problem is turned to be more generic. When old controller is unreachable, an attempt to connect to the member of the old domain randomly throws EAV between failed authentication attempts.
Please, try deleting the Viewer configuration file (config_4.xml) in the %APPDATA% folder. It will be recreated again once you run the Viewer next time. Let's see if it fixes the access violation problem.