Linksys WRT1200AC 2.4 GHz Wifi broken?

First, I hope this is in the right section, otherwise can someone move this to the right section. Thanks

I have a Linksys WRT1200AC, which was running with Gargoyle 1.12, which is based on 18.06. I then tried 21.02 RC3, 19.07.7, 18.06.9 and last but not least 17.01.7. With all but 17.01.7 I have issues of Wifi dropping completely.

My setup is a iPhone SE (2016), iOS 14.6 (latest version) sharing internet over 2.4 GHz. The Linksys WRT1200AC is picking up the wifi signal over 2.4 GHz and sharing it oven 5GHz and lan. When downloading a large file from my iPhone to my laptop connected via LAN, the internet would drop repeatedly after downloading between 30MB-120MB. When that happens, I can see that the Linksys is still connected to the iPhone and the iPhone is showing someone connected but the Linksys cannot send any data to the iPhone.

I noticed during the downloads an increase in ping time (over 100ms) to (ip of iPhone) and many lost pings.

With Gargoyle, running in a terminal window "wifi down && wifi up" would be sufficient to fix the wifi link.

With 17.01.7 there is a fluctuation in download speed and lost pings (28%), but at least the link is not interrupted in the sense that it shows connected but cannot send or receive data.

Long story short, I would call the 2.4 GHz Wifi broken on OpenWRT 18.06 and above.

If anyone needs log files, testing of settings, etc. I am happy to volunteer but I am sure that anyone with a WRT1200AC can easily reproduce the error. I am aware that not many people use the Wifi in client mode, but it should still be considered a basic function.