In 6.0, before deploying the system, we will mention the network & node number for each connectivity server RTA Board settings. Match the settings and apply. Check the settings in SCC-> system setup ->configure system->system nodes. select the node and check the "Properties for advant master connectivity services".
Check the MB300 network object’s MB300 Net aspect for who’s RTA/PU410 you are trying to adjust network number/node.
If the network was added as Net 11, I believe the dialog will enforce network to be set for values 11 thru 19. E.g. 21 won’t be accepted.
A few more images describing your problem won’t hurt.
I am a bit rusty on the SCC Configure System task’s options for ”post deploy” editing of parameters, some allow editing, some don’t. You may have to delete and create a new network in case the network number got wrong
800xA for Advant Master is ”drag ’n drop and export/import friendly”. You can easily move a controller from one network to another keeping the sometimes so crucial object GUIDs.