I still think it's an issue with your Dtv. If no other changes are made to something working, the last change is 'usually' the cause of the problem.
I'm still willing to check around and see if there is a known conflict with your isp and these port ranges. (I should be able to get your isp from the WAN ip.)
[Edit:] check this out and read what 'Malor' said in his review about 1/3 of the way down:
http://www.dslreports.com/comments/3492
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