I rooted my phone recently and have tried to do a software update and everytime I try it says can not connect to network anyone have any clue why it would be doing this?
If you are rooted, the update will fail anyway. Once you root, you probably are looking at waiting for the xda guys to repackage any update that ATT pushes into an Odin flash.
That said, if you look into the Captivate forum on xda, there are several ROMs with 2.2 already available for us. CM is even possible now, but still early beta.
There are also threads there for returning your phone to stock so it CAN receive the OTA update, which includes removing root. If you are going to want to keep root, I would recommend not worrying about the ATT updates anymore and start reading about Odin in the development thread here-