Originally Posted by Raptor23x
Go down in the APN Settings and Change APN Protocol to IPV4, this fixes it.
I just installed Omni ROM after having all the issues with the 2.1.5 Color O/S and not getting notifications. Ever since installing it, it would not work on Cellular data, WIFI only. Sure enough the APN protocol was set to IPV6 and prevented it from connecting. Once I changed this, I instantly connected to LTE! Thanks for the tip.