What sort of speeds should I get with a Deco M4?

My connection is 500Mb.

I was comfortably getting near on full speeds through a wired backhaul Deco.

I've now change internet supplier and have a 1Gb package.

They supplied me with a WiFi 6 router - an AX3000.

However now the PC barely gets above 90Mb through Speedtest.net.  My phone gets to 245Mb wirelessly.

When I use the supplied TP-Link router, I can get 400Mb / 500Mb speeds wirelessly.  I didn't test what I could get wired.

However that TP-Link router isn't compatible with my M4 Deco network, so I opted to use the Decos as I did before.

I have a TP-Link gigabit switch but this shouldn't affect anything?

Should the M4 Decos be able to handle 1Gb internet?