One Rig is not shown - but it's mining

Until yesterday everthing was fine with Hive2 but starting from today my 2nd rig is not shown in the workers list. I already restarted the rig but it isn’t there.

But it’s mining. I can see the rig in the pool. Does anyone have a suggestion what to do / change / check?

Edit: The rig is not even shown as offline. There is nothing that indicates, that there is a 2nd Rig.

And also with the IP:4200 I can’t connect to it?!?