Rocket.Chat App User sync error

Rocket chat 1.2.1 after installation is workin weel, is syncing users, but a while is stopping syncing new user.
After a little search and testing from the app docker container he can’t resolve DC.

If i inspect the container config file the NAMESERVER1 it is ok, but it is not applied.

How can i solve?

Thank you!

i found the problem and the solution.

The problem wast that i was give app permission to user, who don’t have set email address in AD.

When i was completed users information to all who had rocket.chat permission, everything was ok.