The router gave my printer a new address and nothing prints. Do I have to retype it on every device?

No. On the POS open Settings → Printing and press Find printers on this wifi: it lists every printer answering on the network and, for one that has gone quiet, offers the new address with one tap. The address is saved for every device at once, and the Windows app has the same button. To stop it happening again, reserve the printer's address in your router using the hardware address from its self test slip. The POS and the counter tab in the docs covers printers on the wifi.