Starting to implement D717 Deskphones running Firmware 10.1.141.10 (recommended 3CX version)

We see behaviour that these phones lose registration and after about 20 sec. the registration restores itself.
It now appears to happen everytime exactly after 2 min.
However no registration means the phone is unusable, for calling outbound or inbound.

Also found a recent thread about an D735 (although I do not know if this is the same reason, there it is even a more recent version.
And I prefer to use the 'stable' version of software.