You could install Acrylic Wifi Free (https://www.acrylicwifi.com/en/wlan-software/wlan-scanner-acrylic-wifi-free/) and check out the strength of the signal, and that there are not other interfering wifi routers. Many routers work better set to a specific wifi channel rather than left to automatically find one.
Just took a look at that site and the screen shots seem to show a lot of information so I may buy a USB Wifi Dongle (no more free slots on pc) to check
So not sure which ones are good, I won't be using it for broadband, just to be used with that app.
I last used my other modem/router (FRITZ!Box 3390) to see what channels near me was being used and chose one for the 2.4GHz and 5GHz bands on my HH4.
Yep using my HH4 instead of my FRITZ!Box due to issues on line, waiting for it to become stable before I switch back over.