No, your subscribers will not get disconnected.
Their settings will stay intact and their connection to the internet will not be affected.
When your router loses connectivity to ZIMA VPN only the following actions will be delayed until your router connects back to ZIMA VPN:
- Blocking/unblocking/renewing subscribers.
- Editing Subscriber info (such as changing passwords).
- Changing Router / Service Plan settings.
You may troubleshoot your router connection to ZIMA VPN to detect the underlying issue.
However if you have done recent config changes in your mikrotik but unable to remember what could have caused the disconnection you could simply paste again the ZIMA connection script in your router. It fixes the connectivity issues for almost all the cases without any side effects.