What changed in iMessage since ios6 update? Unable to send pics now from Wi-Fi?

This is crazy! My daughter got the new iPod touch 5th gen. It comes with ios6 on it. She is unable to send pictures or videos via iMessage. She has an ID, she is able to send and receive text in iMessage, so she is logged in. This is all of course over our Wi-Fi, since it is an iPod touch…

I have an iPhone 4, a couple days ago I was able to send pictures to her from my phone via iMessage, she would receive them, no problem, just couldn't send them to to me, or anyone else. THEN, I made the horrible mistake of upgrading my iPhone to ios6… Now I can't send her pics and she can't send me pics! Wait, it gets better!

I called apple care to try and fix her iPod, they had me reset the network settings, didn't help. They had me restore the phone completely and set it up as a new phone, no apps on it, not restored from backup, it still wouldn't send pics or vids via iMessage. They asked me to take it into a store and have them look at it (remember my iPhone 4 is now acting the same way since I upgraded it), and when we got to the store and got on Apple's Wi-Fi, it worked! She could send me pics and I could send her pics!

I asked them if there's some network setting I'm missing on my router (also an apple device) to make ios6 able to send mms in iMessage, they had no ideas. They said, reset the router. I did that, and it didn't help, I also removed the apple router because the comcast modem I have also has wireless capability. I setup a new wireless network using the comcast modem, connected both devices to the new network, went into the interface on the modem and disabled the built in firewall, and I still couldn't send pics or vids via iMessage.

Next, I went and parked outside of a local starbucks and tried their network, both devices worked there as they did at the apple store.

My wife then came home with her iPhone 4 that does not have ios6 yet, she connected to the new network that i just set up and she was able to send pics to the iPod just as I was able to before I upgraded. HOWEVER, she can't send them to my ios6, iPhone… Just to the ios6 iPod. AND, neither my phone or my daughter's iPod can send pics to her, just as she couldn't send them to me but i could to her before my upgrade.

OBVIOUSLY, there's something about my comcast network connection that is not allowing this to work, right? But what? A port?

What could have changed in how ios6 relates to my comcast network that is causing this weirdness? If it is a port, why how can I possibly identify it, and how would i open that port if the comcast interface already shows 'firewall disabled', I can't forward the port to a device (even if I did know which one) because I have many devices that will want that traffic, right? (my phone, wife's phone, and daughter's iPod)!

ARRRGGGHHH, Any ideas?

Nothing has changed so far there might be problem in the setting

I think there's no any option to change this setting. You can find a expert who has vast knowledge about that as well as you can go to a expert. So that he can give you a solution. Hope so it would be helpful.