i checked for updated firmware on the d'link dir-615 router back in september when this first happened (after the ios6 update) but the firmware was already up to date - although the last update was 2009.
This was my first clue.
After further research, I discovered that all DIR series products have been discontinued by D'Link. This means that when apple is preparing for a software update, it requests all software/hardware specs from wifi router companies like D'Link, Netgear, Garmin, Cysco, etc. Since D'LInk no longer produces DIR series routers, they did not provide the info. D'Link only provided info for it's newest line of wireless routers.
Leaving all existing DIR users in the dust, with a failed strategy that we'd all buy the new line of wifi routers.
Yesterday, I purchased an Apple wifi router, although pricey at $99, i plugged it in, typed the network name and pw want to use, and it was up and running in less than 5 minutes. The apple router will recieve software/firmware updates just as my iphone, macbook, & ipad does. Everything is working perfectly, and the higher price is worth the convenience and reliability.
If anyone makes it this far, the only thing left would be to check with your internet service provider (comcast, RCN, etc) and make sure you have the most up to date modem. some folks are unable to send text & pic messages on wifi using an out of date modem. (i didn't have to replace mine, but i'm also not having this issue now that i have the new apple wifi router.)
Hope this helps at least a few people out there.