Once you've setup the Slingbox for viewing locally, its the routers responsibility to allow remote viewing. I recommend that check your router's firewall rules. You'll need to make sure that that the corresponding public UDP and TCP ports and being forwarded to your Slingbox's private IP address. Most of the time this problem is associated by only having the TCP port forwarded.
Sometimes, you have to deal with either the broadband provider or WiFi Hotspot either blocking the ports, throttling the bandwidth, or using them for their own nefarious purposes. You can try to work around this by changing Slingbox's default service port of 5001 to something more common like port 80 (HTTP) or 443 (HTTPS). If this is necessary, then you also need to change the port forwarding rules to match the new port number.
IP address and Port Number: http://support.slingbox.com/get/KB-005866.html
Port Forwarding: http://support.slingbox.com/get/KB-2000068.html
Network Setup Assistant: http://support.slingbox.com/get/network-assistant.html
Manual Changes: http://support.slingbox.com/get/KB-5000126.html
ipcctv wrote: (https://community.sling.com/message/13736#13736)
Just swapped 5001 for 443. All working. So, thanks for the tip and shame on 02 UK for this and not having the staff to recognise the problem.
I've been insisting this port was blocked and they kept saying talk to Apple. At one point, they admitted they didn't know how to contact their own network guys and suggested Apple might know. Apple werent any better suggesting I put a complaint against the app or downgrade the firmware.
Once again.. thanks for that..I'd forgotten you could swap ports.
You're welcome. I'm glad to help.