Asus ac86u router slower than new virgin hub

I’ve just moved and upgraded from 350mb to 500mb however was only getting 250mb speeds. I reported this to VM and have got a new virgin hub 5 from a VM engineer installed today. 

The hub is currently in router mode (my old hub was always in modem mode) and the devices connecting to that get the full 500mb. My asus router still works (not sure how) and all devices connected to it still work. 

Logging into the router and running the in built speed test it says it is getting 500mb however, the devices connected to this only get around 200mb. Hard wired via Ethernet seems to be getting 500mb so I’m sure the router is the issue. 

The old hub/router used to give 350mb before moving. 

Firmware on the asus is all up to date.

If I connect to the VM new network, I get the expected 500mb but I would rather use the router as better range on the WiFi and it;s all set up for the whole house. I also din’t want to have to reconnect everything over to the VM network particularly  

I appreciate that this is more a router issue than a VM issue but was hoping someone might be able to assist. 

Cheers,

Affy