Power Hub slow PS5 downloads on 900Mb connection

My Vodafone Power Hub seems to be limiting the download speeds on my PS5 to around 120Mb. I've tried opening the ports, changed DNS settings to Google, disabled the firewall, even added the PS5 to DMZ but it's made no difference. I've swapped the router out for an old one I had lying in a drawer and it works fine and is now able to hit 930Mb. Downside is, I can't use the my landline without using the Power Hub!

I'm actually using two routers in my house. The fibre connection comes into the basement with the Power Hub plugged into the ONT. Then a separate Ethernet cable comes from the Power Hub into a CAT6 socket which goes to the main living area of the house. An Amplifi Alien connects to that socket. I've even gone through all the settings on both to make sure there's no IP conflicts etc.

Every other device when using the Power Hub can hit the full 900Mb, just not my PS5. I've even plugged the PS5 directly into the CAT6 socket to bypass the Amplifi and that didn't make a difference either! I'm quite limited in what I can change on the Power Hub as it appears to be very locked down.

Anyone have any ideas? Thanks

What happens if you directly connect the ps5 into the power hub in the basement?

Are you sure the Cat6 is correctly wired and fully working, allowing a 1Gbps connection?

If there's a wiring fault with that cable it could be running at 100Mbps...I know this is less that the 120Mbps that you're seeing but that <could> be a rounding error

Or a broken pin in the router. Try plugging the PS5 into a different port on the router. But indeed, I'd expect to see ~100Mbps not 120Mbps.

In any case, how are you measuring this? Is there some sort of speedtest app on the PS5, or something browser-based? A more realistic test is to measure the download time of a large game. That is, the problem could just be an artefact of your speed testing.