Connect new mobile devices via Application

Hello, everyone!
I have a question regarding Self-Hosted Mattermost.
I have 2 servers with different subdomains and
Everything was fine for a while, but then one of my coworkers said that he can’t connect from his mobile app to both instances. The curious thing is that everyone who was already connected to the mobile app could connect and disconnect. But when connecting from new devices, we get an error that the server is missing a DiagnosticId. The server has been rebooted, updated, nothing in the logs. DiagnosticId is present in the database. Not a Docker container.
Mattermost Version: 9.8.1
Database Schema Version: 120