Please try the following settings in CommCat Mobile:
Remote Radio: K3/KX3 (thru Internet). TS-2000 (thru Internet) should also work.
Radio IP: RigPi LAN address (when home) or WAN address (when away)
Radio Port: 30001 (unless changed in RigPi, see CCM Port in System Settings.
Note that the CommCat IP and CommCat Port are not used, they can stay whatever they are. Using the “(thru Internet)” setting for radio means a direct connection is being made to a radio (RigPi) that does not go through CommCat. CommCat Mobile communicates with RigPi using the Elecraft/Kenwood command set. RigPi converts those commands to the Hamlib commands for the radio you have selected in RigPi.