I've had my XR18 for about a year and a half now and continue to be impressed with its capabilities and value. Probably one of the best "bang for the buck" gear investments I've ever made.
I never used the internal router and initially used an old Netgear unit. A few months ago I switched to this little Mikrotik box
Amazon.com: RouterBoard hAP AC Lite Tower: Cell Phones & Accessories to gain dual band capability. It's very small, has no external antennas and has worked flawlessly. We connect the FOH tablet and three smaller tablets for monitors, the wired laptop, wired Driverack and lighting controller interface through the Mikrotik and it hasn't hiccupped yet. It's velcro'd into the back of my rack.
Yes you can wire the laptop direct to the XR or as I have, just keep it connected through one of the ports on the router along with the laptop.