Prior to performing this procedure, the phone line and ADSL connection need to be isolated as a potential cause for any issues. This procedure does not check or isolate other external causes. Please see other relevant KB articles.
Isolate whether the problem is the modem or the RouterBoard:
1. Power cycle the modem only (wait ~5 minutes for it to sync and settle, while monitoring the RB logs for a successful connection -- be careful not to change any config or reset anything in the RB at this stage)
2. If the connection does not re-establish after waiting 5 minutes, reboot the routerboard and see if it comes back
If step 1 resolves the issue: The modem may need to be replaced. As a test to confirm, a temporary alternative modem may be used. Please note that in this instance there is also a good chance that the issue may be connection related, so a modem replacement is not a guaranteed fix.
If step 2 resolves the issue:, then the following steps needs to be performed on the RouterBoard:
a. Configuration review (check for any loops / conundrums / inaccuracies / firewall weaknesses in the configuration)
b. Update the routerboard firwmare from http://www.mikrotik.com/download
These steps are typically intended to be followed as part of a support ticket troubleshooting process. If these steps do not lead to a resolution, please update your related support ticket to advise the technician.