Best way to route

So as of right now I have Sophos running on a r610 server with Proxmox and I am only using 2 of the 1 gig nic. My question is what's the best way for me to disable to home cable modem DHCP and force connected clients through Sophos. Would setting the DNS be a good route? Next question is can I setup a Linksys 1900ac router on a third nic and use Sophos to control WIFI settings under Sophos wireless like as ap? I can install dd-wrt. I'm a little confused what is the best route and setup for that.  Thanks in advance for any help and support. New to Sophos it's a little learning curve.

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[edited by: emmosophos at 4:54 PM (GMT -8) on 26 Nov 2021]