Here are different ways to prevent randomly restarting router issue:
Set Automatic Channel Setting
Set the automatic channel setting for your channel. It won’t work if you’ve picked a specific channel from the list.
Switch your Network
Are you currently connected to a 5 GHz network? Do connect to a 2.4 GHz Network.
Disable Security Features
Check the status of advanced security features such as Network Isolation, Wi-Fi Protected Setup and Address Filtering. If any of these features are enabled, disable them.
Change Network Mode
Are you using a Wireless Internet pack? Set the network mode to Mixed since higher modes reportedly caused router restarting issue.
Restore Router to Factory Defaults
Resetting the router involves setting all factory defaults. After restoring system defaults, you shouldn’t experience the issue anymore.
Customize MTU Size and Other Settings
Bring down the MTU Size from 1492 to 1472. Turn off SIP ALG feature. Save the changes, restart your router.
Change Bandwidth Settings
You can configure the bandwidth settings from QoS Setup menu after opening up the Router’s web based interface. Just use 192.168.X.X in your browser’s address bar. Contact your Internet Service Provider for more information on opening Router Config Page. Enable Bandwidth Control and increase the Uplink Bandwidth to 499 kbps. You may have to switch off and switch on the router for the changes to take effects.
Disable Incompatible Features
Some users reported that the router restarting issue fixed after disabling incompatible features such as UpnP.