Is it possible to suspend laptop cloud or Nas backups when away from home and tethering a mobile phone as internet connection?
Not directly in the app, no.
You could do a pre-backup command though that pings for your NAS and if no response, then the backup would not continue. I can't find the other forum posts that someone asked this, but I believe it was MVP Steve Smith that had some additional documentation on how to set this up. You might want to send him a PM with the link to this thread.
Mike, thanks for the PM on this question.
Please see the attached document that I created a little while back that should help you on this matter by using a Pre Command to test for the presence of NAS resource and only continue with a backup if this test is successful.