Is it even possible to use the Extreme print server in bridge mode?
Recently I took out my 2-year old Asus AC68U. After moving to EdgeRouter 4 and Unifi AP, I had no use of it until now I figured I could use it as a print server.
I had asuswrt installed on it long ago (it isn't necessary), and then I had it configured as an access point because that's the most logical method. I static-mapped its IP, then I deactivated the 2.4/5ghz radios and connected my canon printer to the usb 3.0 port on the router. So now the AC68U is essentially a print server.
All wired devices have no problem printing with it. To facilitate wireless printing from my iPhones and iPads, I have HandyPrint Pro installed on my Mac Mini which I have powered on 24/7. Everything works just fine as it is.
I do have an AirPort Extreme as well but I just couldn't find it currently from my storeroom.
If there's a way to deactivate the radios on the Extreme, I highly recommend you do it. Your currently implementation is correct albeit having wifi signal coming off from it might create interference with your existing wireless networks.
Bridge mode will not work. At least not that I know of.