Well, after working fine for a couple of months my router once again started resetting about 2 weeks ago. It reset at least 3 times in 2 days. I checked the settings on the extender and it was still...

@msnsaf, Make sure you have updated your firmware. The functionality is available on my HS105 plugs and HS200 switches. It is NOT available on my HS107 plug.

@DRBG, It's not in app's Settings; it's in the device's settings. Select the device from the Devices page. Then press the gear (settings) icon in the upper right corner. Then select Device Info.

It's been a week now with the new settings and I haven't noticed my router reset even once during that time. So I'm going to call this fixed.

@Carl, Trying your suggestion now. I've enabled only 5G from extender to router/host and enabled only 2.4G on the extended network. We'll see what happens. BTW, there doesn't appear to be a simple...

Does anyone know where to find the 'High Speed Mode' setting?