RMS has recently underwent multiple updates to improve stability and load distribution to avoid similar issues. Hopefully, this will help improve connection to RMS quality in the future.
If you still have devices offline, could you try reinitiating connection to RMS by sending SMS to the device with the following syntax:
- <device_password> rms_connect
Replace <device_password> with the password used to login to router's WebUI.
If physical access to the devices is possible, the following can be attempted: login to the device via SSH and execute the following command:
- /etc/init.d/rms_mqtt restart
Lastly, could you login to the device's WebUI Services -> Cloud solutions -> RMS page and check, if there is a Connect button? If it is, press it, otherwise unregister device from RMS and re-add it again.