I was also having issue with my Epson WorkForce 545 and AirPrint using my iPhone 5s running iOS 9. Tried switching from my iPhones 5gHz WiFi frequency to 2.4gHz like the Epson but nothing.
What did work was going to my PC to find out my routers name like Briansyddall mentioned. This was vital yet only half of the solution.
On my PC I opened up a Windows Command Prompt and typed in:
ipconfig /allcompartments /all
The last line in the first section of network information results should read
"DNS Suffix Search List" or the first line of the next section should say
"Connection-specific DNS Suffix". This is where I found my routers name. In my case
fios-router.home
From here I opened up a web browser on my PC and typed in the IP address of my Epson 545. Printing your Network Settings under the printer Setup menu will indicate what your printers IP address is (be sure to also copy down the printer name exactly as it reads on the printout). In my case:
http://192.168.1.150 and "my545".
Connect from your PC to the Epson via a web browser and the printers IP address. You should see 4 or 5 options. Among them is
AirPrint Setup. Click it. Under
"Bonjour Service Name" leave the default printer name (Epson WorkForce 545) alone unless you personalized the printer name during initial Setup of the printer like I did; therefore in my instance I typed "my545". The next field is key:
"Bonjour Location" means "router name" as described above! Type it in!
AirPrint SetUp Complete!