How do I get the iPad linked again?

[Studio]

Hi I have an APPLE cash register and 1 customer screen. these have always worked well but with an update not anymore.
Now i have tried everything. IP adjusted, tablet restarted from (both) router, etc. etc.
Every time the system indicates at the link "customer screen is already linked to another POS"

HELP how do I get the ipad linked again?

[Studio]

Problem solved, I have completely reinstalled the iPad and reconnected it. Problem solved