My ipad can’t find my printer since having a new Virgin Router

The Canon iX6850 is listed as a supported model in About AirPrint - Apple Support.

An Ethernet printer connection to one of the LAN ports of a Wi-Fi router is a good thing. This is usually stable, and rules out some of the problems related to wireless.

Extra apps should not be needed.

See also Use AirPrint to print from your iPhone or iPad - Apple Support.

To begin with, after checking all settings/connections, you may want to try a full power-cycle sequence:

Power off the Wi-Fi router, the printer, the iPad(s) and the iPhone. 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(s) and the iPhone. Any change?

For further troubleshooting, see the following user tip by Lawrence Finch:

AirPrint Troubleshooting - Apple Community

Thank you for the information. Depending on the exact router/gateway model and the type of connection, it may be necessary to wait for a relatively long time before the broadband connection has been established after power cycling. However, AirPrint relies upon the local network, so printing should work as soon as the LAN is operational.

Anyway, hopefully the engineer can help you solve the problem.