VPN Not Working After Unlocking Phone

I had a VPN with Cisco on my iPhone 5s, and it worked fine for a few weeks. I unlocked my phone through AT&T the other day, and even though I was able to use my VPN after I unlocked my phone, my VPN now does not work. Previously, when the VPN couldn't connect, I would get a message saying that the VPN couldn't connect, now I don't even get that message. The VPN just stops trying to connect after a few seconds. I don't know if this could be caused by the unlock? I got a new SIM card after I unlocked my phone as well, but the VPN was having problems before that.

Any thoughts are appreciated. Thanks.