Overnight speed drop. ax3600 MR80. Anyone?

Hello,

So I installed a ax3600 / MR80 on 07/20/21.  Did a manual firmware update to the router and satellites. since the auto update wouldn't find the new firmware. now the installed version is V1.1.5.4_3.1.91.  

After and before the update I was getting a consistent 230Mbps down and around 10 up.  this morning I woke up to a speed under 6Mbps.  Tested on speedtest app . running on iOS, Dslreports.com running on iOS safari and also a Macbook and Windows machine.  got the same result.  but of course the Netgear app shows over 200Mbps righ after the speedtest app.  waited an hour and retested and same thing.  finally did a router reboot and tested again.  speed is back up to over 200Mbps. 

Has anyone experienced this?  I'm keeping an eye on the router before support runs out.  Just in case I need to return it.  but also got the extended warrany from best buy. 

I'm hopping this is not the router's norm.  because when it works.  it works pretty good. 

Oh, and all iOS devices, Mac and Windows laptops are running the latest OS.

Thanks