Unstable Netgear WNDR3700 v4 WiFi

Hello, I am new to Openwrt and recently flashed my Netgear WNDR3700 v4 router. I like the new interface and features but unfortunately WiFi stability is very poor. Almost daily WiFi lockups cause me to have to reset the router. I read that 5G radio is a problem with this router but disabling it didn't make a difference.

I would love to get Openwrt working but if that's not feasible, I would like to go back to original firmware. I am having difficulty doing that as well. I'd appreciate any suggestions.

Here is the version I am running:

OpenWrt 22.03.5 r20134-5f15225c1e / LuCI openwrt-22.03 branch git-23.093.57104-ce20b4a

I have used wifi on this router for a long time without any issue. You may have a bad setting or a hardware issue as this device is rather old.

To go back to Netgear firmware, use nmrpflash method. You may have to test different timings between switching on the device and launching the command. At the end it works. I have done it several times.
(If you are under windows, use ncap 1.60. I had trouble with version >1.60)

I don't know about your WAN link, but consider this device as outdated. It can't correctly manage a high speed as provided by FTTH. I still have mine, and consider it as a spare device, or a secondary AP for low end devices.