Well in my case I had an old computer with an i5-6400 laying about. Running 1 gig PPPoE only taxes the CPU to about 23% momentarily.

However, if that's not an option, you can get an Intel N100 based tiny PC which is more than enough for the task.

In reply to a post by Cheule:

Well in my case I had an old computer with an i5-6400 laying about. Running 1 gig PPPoE only taxes the CPU to about 23% momentarily.

However, if that's not an option, you can get an Intel N100 based tiny PC which is more than enough for the task.

What you have to look at is energy usage, remember a router has to stay on 24/7. I got myself a Dell thin client to muck around with Home assistant, but I could not get the computer to connect with it, so gave up at the moment.