I have several iOS devices with Telus SIM cards all of which will fail to connect to my Slingbox over mobility but work fine over wifi. However, if I insert an other carrier's SIM card I am able to connect to my slingbox without issues. This has happened probably sometime after Christmas as before that time I could connect over mobility without problems. Of course I have gone through the usual of resetting devices etc to rule out the rest of the hardware. Everything points to the mobility network.
Edit: I have confirmed that Telus blocks sling content over its mobility network by installing a VPN solution on my devices and my sling players are now functional. So now the question is why? So I am now shopping for a new provider.