I have a lot of disconnects from the tablet to companion while editing songs in Companion.
It occurs every 2-3 songs.
Also the companion app crashes a lot (spontaneous closes).

I use the Companion App on Windows and Tablets running Android.

Any idea how to troubleshoot this and solve this?

Version 4.1.7 of the companion app will be released today or tomorrow with a few important fixes. These may help with the connection problems you are encountering. 

On a side note, it may be worth using your phone as a WiFi hotspot to see if the problem is related to your router or network in any way. If you no longer get disconnects, then it is. If not, then we'll need to see if 4.1.7 resolves the issue.

Mike