Hi guys

I have just had fibre set up with Bigpipe (100/20 plan), and am having some speed issues with my router. I have tested the connection by connecting directly to the ONT with a PPPoE connection and got approximately 100 down/20 up, however when connecting through my router I'm getting approximately 48/15. Any ideas on what could be causing this speed reduction? QoS is already off and I can't find anything obvious in the settings, however I'm definitely no expert so I'm probably missing something.

The router is a DrayTek 2860n, all tests being run over ethernet cable on a Windows 10 PC. Any advice would be great.