You mentioned you have VDSL. So you’ll still need your VDSL modem.

You will probably be able to configure it in pass-through mode or something similar so it will only do the modem functions and not the routing functions.

Then you can use anything you like as a router.

I use OpnSense on a diet cheap ex-lease x86 SFF desktop. I also filled it with PCIe NIC’s. The only down side of that is it’s power-draw.