AppOfflineError: Connection to server failed -- custom URL

What I’m trying to do:
Use the app.
I get the message AppOfflineError: Connection to server failed (error)

What I’ve tried and what’s not working:
The code works in the developer and fails now from the custom URL. I am extensively using the UPLINK I have not changed keys for uplink, but this app has been working properly for more than a year.

Can someone advise?

Thank you,

JM

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