Printer connection using Airport Express with Plusnet broadband

[#1]

I have just received a new router from Plusnet. I have successfully connected a Mac desktop, an Ipad, an Iphone, and a Mac Book Pro but I can not get my printer to connect. My printer is cable connected to the Airport Express. In my macbook pro, system preferences, under network it says my airport express is connected to my plusnet broadband. In the printer section of system preferences it says my printer ( cannon ip3000 ) is not connected. Any ideas what is wrong?  The printer worked ok with my old router.  Thanks, Alan

[#2]

The Airport Express (and therefore the printer) will have changed IP address so you'll probably need to edit the properties of the printer to reflect this on the Mac?

[#3]

Thanks for the suggestion. An idea how to do this?  Alan

[#4]

Settings|Print & Fax and then 'Options & Supplies' will show where the Mac thinks the printer is.  No idea how to change it other than adding a new printer and then deleting the old one.
How did you add the printer in the first place?

[#5]

The original set up was done by an Apple speciality company! The printer appears to be connected but still can't print. The airport express is still flashing amber, but it says it is connected to my Plusnet broadband.  Alan

[#6]

Is the printer using WiFi? A new router will have a new wireless key, so the printer will probably need to be re-installed to work with your new router.