I've had the ARCHER AX11000 router for about 5 years now and for the most part, it has worked well.
In the last year however, I've had some strange problems with it.
My network consists of an audio recording studio with 2 high end windows pc's, 1 older pc, smart tv, home alarm system, phone, etc.
It has one extender but its not mesh.  All pcs are windows 10 machines 64bit.

My Cox service is 500mb/s download and 50mb/s upload.

Test speeds work well and the system can handle lots of 4k videos running together.
But when it comes to loading web pages, all 3 pcs have occasional issues with incomplete or no load situations requiring a refresh to try again.

The old pc is the worst.  Sometimes a refresh is not enough to get a page to properly load.  It has the worst symptoms with government pages with forms and doctor portals with more forms. 

It may load portions of a web page but buttons or parts of forms or other widgets may be missing.

Even has issues with loading YouTube pages.  Also, the smart TV will require refresh as channels will fail to load properly at first.  And if a show has a commercial, the video may not resume properly afterward; requiring a rewind to get the video going again.
It seems like it's some type of timing/protocol issue.
I don't know if it is the Cox service or the AX11000 router itself.
When the problems first started, I thought it was my pc.  But then all 3 pcs did the same thing to varying degrees.

Once a page is loaded properly, then all is well after that.  Plenty of speed to run numerous 4k videos simultaneously no problem
It's just that initial connection where things are going wrong.

All 3 pcs do have Malwarebytes and System Mechanic protection and I've been curious if those programs are doing something wrong.

Does anyone recognize the symptoms my network is having and can you say more about what the issue may be and how to troubleshoot it?
And even if you don't know, can you suggest how to get a network expert to look at it remotely or in person?

Thanks, Allen