I'm having problems installing printers on Iprint. Everytime I click on the printer to install it, IE pops up an error:

Errorcode: 10060
Error message: Winsock 10060 - Connection has timed out

Error group: WINSOCK
Error code: 10060

Iprint server is behind NAT firewall and I've opened ports 80,515 and 631.
Am I missing anything? Any ideas? Thanks