Fixing a printer - router IP mismatch

If you can't print, it may be because the IP address the printer has set is incompatible with your router's settings.

To fix it, go into the internet router's admin panel. (It's usually at http://192.168.18.1 or http://192.168.0.1. The username and password are usually on a sticker on the bottom of your router. If this doesn't work, check your router's manual as some require https:// or use a different port such as 8080 or 8443.)

Somewhere in the settings you should see the following values: Router IP address Network subnet mask DHCP IP address range, or DHCP start/end IP address

The subnet mask is most likely 255.255.255.0 or /24. In this case, allowable IP addresses will have the same first three sections (e.g. 192.168.0.x or 10.0.1.x), but the fourth section can differ. If it isn't, you will need to use an IP address subnet calculator to figure out what IP address range you can use.

There are two approaches to set the printer's IP addresses: setting up a static IP address, and setting up a DHCP reservation.

If you are using a static IP address, then your printer's IP address needs to be within the IP address range for the subnet, but outside the DHCP IP address range. It also cannot be at an IP address ending in .0, or the first or last IP address within the subnet, which if your subnet mask is 255.255.255.0, would be .1, and .255. If the DHCP IP address range is taking up the entire subnet, you can reduce the end IP address by a few to make some room. Don't reduce it too much, or there won't be enough room for all your other devices.

Alternatively, if you are setting up a DHCP reservation, you will need the MAC address of the printer. This may appear under connected devices in your router, or for Riso machines with a touchscreen, may be visible there. It may also be on a sticker on the network interface card inside the Riso, for older machines. Otherwise, you may need the "RISO Console" software to find it. Then follow the instructions for your specific router to set a DHCP reserved IP address. This IP address will have to be within the DHCP IP address range, and then will behave as if it is static. The printer will need to have DHCP enabled for this to work. If you have issues with the printer not pulling an IP address, it is safe to set a static IP address on it, as long as the IP address is the same as the DHCP reserved one in the router.

Setting a static IP address within the DHCP IP address range, that is not reserved, can lead to IP address conflicts, as the DHCP server could give a different device the same IP address as the printer. This would lead to neither device being able to access the network at all.

The printer's IP address must be within the same subnet as the router and the computer, which in most cases means that the first three sections of the IP address will be the same. It cannot be .0, at the beginning (usually .1), or at the end (usually .255) of the subnet.

To set your printer's IP address, go back to your printer and click the "System" tab and the "Network Settings (IPv4)", click the box with the numbers you want to change, hit the clear button, and enter the new IP address on the keypad. (More detailed instructions for editing the IP address: How to install the Mac printer driver for risograph machines). If you are enabling DHCP on the printer, you may have to reboot it to take effect.

Then remove and re-add your printer with the new IP address. With either approach, the IP address should not change.