Try reserving the IP address for the printer in the router
To do this you will need to know the MAC address code for the printer
Usually is it printed on the back of the printer somewhere, probaly near the serial code
You will also be able to see it, if it is connected to the router.
Open the router config page and click on LAN Setup
Take note of the MAC address for your printer if it is connected, also take note of the device name.
Once done, turn off the printer so it is not showing in the list (you may have to refresh the page)
Now click on the add button
On the next screen type in an IP address to reserve.
Try using 192.168.1.25 as a suggestion
Now type in the MAC address and the device name in the relevant column
If you do not have a device name then place a suitable one in such as Dell_Printer as a suggestion
Once done click on the apply button for the changes to take effect
Please note:
If you need to reverse the changes then simply go back to the address reservation table, choose the item we reserved by selecting the relevent radio button at the side and click on Delete, then apply the settings and your router will be back to how it was before we started the reservation.