No, the print server address is reserved in the router and the print server is set to automatic - 'use DHCP'. I always reserve devices in the router, never in the device itself.
There is no new firmware for the print server and the connected printer is an old USB Brother laser printer HL-1430, so only basic driver of Windows.
It always works, also when it is not displayed in the connected clients display. The printer driver contains the IP-adress by the way; hostname does not work.
In my other routers (1 TP-Link and 2 D-Link's) I always saw it, but sometimes only with the mac-address and not the IP-address. I think it's a glitch in the print server firmware: pity, but not disturbing operation of the printer.
I have another Brother real wireless printer connected and also reserved in the router. In the printer driver it connects by it's Hostname. It is always in the list.
So the print server has an IP address ON the printer server and not the router right?
Seems like this maybe a printer server issue possibly. is the print servers FW up to date? Seems like if the router is rebooted the printer server fails to handshake with the router to let it know that it has an IP address, static and that it's online. 
I haven't had a chance to test guest zone yet. I'll try this weekend.