I replaced Asus as main router with OPNsense in 2016 and it is working perfect I have Xeon E3-1265Lv2, 16GB (2x KTH-PL316E/8G), HP 331T (LAN bridge) using hypervising Proxmox and VM OPNsense
Asus I am using as AP wi-fi mode
https://docs.opnsense.org/manual/ips.html