I bought this router on Feb and it has been working fine. The problem started after I decided to update the firmware sometime last week (didn't remember the exact date). This update was done using the online update feature, not through local update, so I'm pretty sure it's not because I downloaded the wrong firmware version or something.

Since then, I've had crazy unstable ping with massive ping spikes and sometimes just outright disconnect for a minute or so before it connects by itself again. I'm pretty sure the router is the problem because if I connect my PC directly to the modem, it works fine without any issues. I've tried the regular turning off and on again countless times, even factory resetting the router twice and the issue persists.

Below attached some ping test results that shows those massive ping spikes. Note that that ping test is done from my PC which is wired through ethernet to the router, but this issue affects every device that is connected through WiFi as well.

Any help would be appreciated as this problem has affected my work (and gaming time) quite significantly.