Was rather shocked to find BT hubs don’t allow you to change DNS servers anymore and force you to use their own ones, so I can’t properly setup adguard.
What routers are people using now that are reliable and will let me control my own network configuration
If you have a pi kicking around or a docker instance of pihole you can use it to take over dhcp of the router and then set the dns servers in pihole.
That’s what I do currently on my home hub
That might be the way to do it. I’m somewhat unfamiliar with networking, what does DHCP do?
DHCP strands for dynamic host control protocol. It is a server that assigns dynamic IP addresses to devices on the network which request it.