Using TPLink Archer AX1500 5 GHz wifi router and fibre internet

I have a problem with these 3 websites

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they intermittently fail (timeout) on my windows 11 pc  - ping and tracert also fail.  tracert fails at the last hop
The 3 websites (or ping) either all succeed or all fail.  larryco doesn't support ping

Turning wifi off and on at my PC makes it work for a while, occasionally it recovers by itself.

It never fails with a VPN running - stop the vpn and it fails

It fails on two different windows 11 PCs with different wifi hardware - but sometimes one works when the other is failing

It fails on my current machine with a tp-link USB wifi adapter instead of the in-built wifi (mediatek mt7902)
I've never seen it fail on my android samsung phone going through the same router (i.e. not cellular)

It fails for both wifi 5 (ac) and wifi 6 (ax)
Changing a setting such as WOWLAN on the mediatek MT7902 wifi properties in Windows makes it start working - i think due to the wifi card resetting itself.

I upgraded the router firmware and it still fails.  I've tried a lot of suggestions from chatgpt but the failure continues.  According to chatgpt, it's a state de-synchronization problem.

Any ideas for how to stop it failing or how to find out why it fails?

[Mod edit (MF): removed URLs]