x86 makes a great routing platform (although possibly overkill and likely with higher power consumption when comparing against all-in-one wifi router). But x86 is generally a terrible wifi device insofar as the limited performance and functions of the wifi hardware (USB and PCI cards).
An all-in-one wifi router or a proper AP will usually run circles around x86 for actual wifi performance.
If this is your full internet speed, most wifi routers made in the past 5 years (maybe more) can handle this throughput without breaking a sweat. The equation is different if you'll be running VPNs (especially if you use an older/bloated VPN protocol like OpenVPN).
In your case you're using this as a router, so there's still value in your setup, but I'd recommend that you look at purpose built APs or wifi routers.
BTW, see this thread where the OP was trying to make a dumb AP out of an x86 system....