WiFi print

If set-up correctly, should you continue to experience difficulties, your WiFi Router may be unexpectedly failing to pass Apple Bonjour traffic on you local network - or your WiFi Router or Network Switch may be blocking this device discovery protocol.

The Apple Bonjour protocol uses mDNS (Multicast DNS) UDP port 5353.

You may find that restart of your network components will resolve the problem. You’ll need to restart your network devices in the correct order. Assuming that you WiFi Router provides DNS services for your network, restart devices in this order - allowing time for devices to fully boot/restart prior to restarting other devices:

• WiFi Router
• Upstream wired Network Switch(es)
• WiFi Access Points / Network Extenders
• Other fixed infrastructure devices - such as Printers
• Client devices

Restarting your iPad, after restarting other devices in the correct sequence, is most simply achieved by a forced-restart of the iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If you continue to have difficulties, check to see if your iPad is using the new WiFi Private Address feature. This feature is intended to provide additional privacy and security when using “public” (untrusted) WiFi networks.

Settings > WiFi > [Your WiFi Network / SSID] - tap the “i” icon - Private Address

The Private Address feature is largely unnecessary for your home WiFi network; if enabled, Private Addressing can interfere with anticipated operation of other devices, such as AirPrint. In such circumstances, you may need to disable this feature - and can be enabled or disabled for each individual network.

Use private Wi-Fi addresses in iOS 14, iPadOS 14, and watchOS 7 - Apple Support

Hi,

Would it be correct to assume that it is an AirPrint-enabled printer? Exact Brother model?

For AirPrint, the printer and the iPad must be connected to the same network (Wi-Fi router).

About AirPrint - Apple Support

Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support

If there is a problem with AirPrint, and if all settings are OK, you may want to try the following complete procedure (in the exact order):

Power off the Wi-Fi router, the printer, the iPad, and all other devices/computers. Wait two to three minutes. Power on the router. Wait two to three minutes. Power on the printer. Wait a minute or two. Power on the iPad. Finally, power on all other devices/computers.

If necessary, post back with the modem/router model (please do not post serial numbers or access codes).

When you changed your modem, did you reconnect your brother printer to the network? Your iPad likely can't find the printer because the printer also had to be reconnected to the network thru the new modem.