This is a very generic issue.
It might be faster to open a support case.
some things to check
1) make sure the robot on the primary and ump are both running 7.91 or igher
2) make sure the hub on primary is running 7.91 or higher
3) try restarting the primary and the ump robots
4) set the wasp probe loglevel to 3 and logsize to 35000 and check the wasp and portal logs.