Can try with these methods:
1 Check UE connection in Client PC with UDM.
2 Reactive APEX data client TestDriveIIListener.exe in client PC,can be found in folder: C:\Program Files\Spirent Communications\APEX Data Client
3 Re-install UDM both in Control and Client PC
4 Re-install UTS driver
5 Re-install data client both in Client and Server PC .