Hey! Broadband - using own router

Hello - hoping for some guidance, please. I've recently had Hey! Broadband fibre installed to our home with a separate ONT and router provided. I've discovered that the provided router (Linksys Velop MX4000) is not quite as configurable as my previous FritzBox router and would like to revert to using that.

Using the Linksys router I can routinely get down and up speeds of around 400Mbps. When using my Fritzbox router I only see speeds of 30-40 Mbps, though it seems to be otherwise working.

I haven't specifically requested 'Bridge mode' to be configured and have simply taken the ethernet cable from the ONT and used it in the LAN1 port of my Fritzbox router and configured it as DHCP (no VLAN setup).

I can't figure out why the speeds should be so significantly different. Would anyone please be able to help troubleshoot or suggest what to try?

[Additional info: The Fritzbox router is old - it's a 3490 - and certainly can't handle gigabit speeds. But I expect it should be able to handle 3-400 Mbps?]

The first question to be resolved is whether your LAN connection to the router is wired or wireless.

If you are connecting with a physical cable (not wireless) then It could be a configuration issue. I'd suggest resetting the Fritzbox to factory settings and setting it up from scratch.

I had a 3490 and got 900Mbps up/down with it (before upgrading to a newer router). See my old thread here: https://forums.thinkbroadband.com/multiuser/4707641-...