@BugattiVeyron 

Even though the extender doesn't support OneMesh, it is still compatible with the router.

There are a few different cases related with unstable connection, including WAN connection unstable and wireless client devices unstable.

For WAN connection unstable (Router Internet LED turns red/orange occasionally):

    1) Connect a PC directly into your modem to verify if your ISP Internet is stable.

    2) Make sure the Ethernet cable between your modem and the Router is connected properly, replaced old cables with new ones.

    3) Change the DNS Server of the Router, login the web management interface of the Router, go to Advanced > Network > Internet > Advanced Settings, change the two DNS Servers into 1.1.1.1 and 8.8.8.8.

    4) Go to Advanced > System > Firmware Update to upgrade the firmware of the Router.

For wireless client devices unstable:

    1) Make sure the Router is properly placed, it should be put in open area instead of inside a cabinet or shelf.

    2) Login the web management interface of the Router, go to Advanced > Wireless > Wireless Settings, change the wireless channel into another one.

    3) For 2.4GHz wireless client devices, adjust 2.4GHz channel width into 20MHz, for 5G wireless client devices, adjust 5GHz channel width into 80MHz or 40MHz to avoid interference.

If the issue persists, please let us know if there is any LED changes on the router when the issue happens, whether all client devices will lose internet at the same time, or just wireless clients disconnect from the WiFi and requires to reconnect manually.