Started a new company and now not syncing with Square app. Also on disconnect, it sends message to app center but bad Gateway returned. Support unable to fix, ideas?

1st support mentioned issue with multiple companies, we got disconnected. 2nd support told me not QB and call Square, Square said not their issue as app developed by Intuit, 3rd and 4th support unable to help. 4th support mentioned maybe multiple PCs used to connect to square app causing it but unable to disconnect successfully.