When I video call my wife she complains that after a few minutes the picture is not clear. I turn the video off and back on and it is clear for another few minutes.

I re installed Skype but it is still the same. Cam works fine for me on my computer.

Any tips?

Sounds like a connection/service issue on the Thai side, if there are more on the network at a particular time of day the service will be degraded.

Sounds like some sort bandwidth shaping going on the the internet network connection. This will be outside your control. Will be one of the ISP involved I would say.