When I was testing the router, it suddenly started to lose connection. I tried to restart the winbox and the router several times but it didn't help. I then reset the router but the problem still there. After I login with winbox for a few seconds, the error message "Router has been disconnected!" pops up, and then a few seconds later, another message "Could not connect to 00:0C:42:F4:79 (port 20561) - other end is not responding!". I've checked all the cables and power cord and they are totally fine. Did anyone experience this problem before? How to fix this? Please advice. Thank you very much.

You are connecting to the router via MAC address. If you want to keep doing this, make sure you disable any other network cards, bluetooth, VM virtual adaptors, etc...

A better solution is to connect to it via IP address.

i have same problem in my rb750 is anybody know how to fix please reply