@John20 

The printer may have different network settings then the router. For example, the printer may be configured for 192.168.1.10 while the router is on 192.168.0.x.

Make sure your printer's network is set for DHCP so it grabs the correct IP from the router. You can also log into the router and look at the DHCP client list to see if the printer is there.

@John20 I'm having the same problem. In fact I disconnected mt TP-Link router and re-connected my old router. Everything worked perfectly. Then switch to the TP-Link and it didn't work.

@jeff-the-chef 

I rebooted everything including the printer and it works for me now.

Make sure both the printer and iphone are on the same network. If the iphone is on guest network, then it might not work.

@John20 Me too I have same problem with the C50, yesterday I updated firmware but nothing ... I broadcast activated etc etc but nothing ... too bad a problem a bit 'unexpected...

I found a solution by connecting it via usb and then installing this app https://www.decisivetactics.com/products/printopia/ then the service is seen (on the mac)