I've just recently moved across town. Previously, I had Dynamic DNS set up so I could remotely connect to my desktop (primarily to use TightVNC). My ISP was Comcast and I'm in the Denver, Colorado area.

Currently, I'm still with Comcast and still in Denver. My router connects to the internet just fine and my Dynamic DNS record over at DynDNS did get updated with my router's current external IP address. So my router, DynDNS, and public DNS records all agree what my IP address is.

However, I can't actually connect to anything from the outside world. My trace route to Google looks something like:

Tracing route to google.com [74.125.19.147]

  1     3 ms     1 ms     1 ms  192.168.1.1 (this is the internal IP address of my router)
  2     *        *        *     Request timed out.
  3     9 ms     8 ms    10 ms  te-8-2-ur02.wheatridge.co.denver.comcast.net [68.85.221.177]
  4    12 ms    12 ms    19 ms  te-0-8-0-2-ar02.aurora.co.denver.comcast.net [68.86.103.97]
  5    16 ms    13 ms    11 ms  pos-0-3-0-0-cr01.denver.co.ibone.comcast.net [68.86.91.1]
  6    28 ms    28 ms    27 ms  pos-0-9-0-0-cr01.dallas.tx.ibone.comcast.net [68.86.85.174]
  7    29 ms    27 ms    28 ms  pos-0-1-0-0-pe01.1950stemmons.tx.ibone.comcast.net [68.86.86.94]
  8    66 ms   108 ms     *     75.149.231.70
  9    65 ms    68 ms    93 ms  72.14.233.77
 10    67 ms    66 ms    66 ms  72.14.233.111
 11    67 ms    67 ms    69 ms  216.239.43.144
 12    68 ms    71 ms    73 ms  209.85.249.30
 13    66 ms    66 ms    68 ms  nuq04s01-in-f147.1e100.net [74.125.19.147]

This is what the trace route looks like from an outside source to my DynDNS domain name:

traceroute to 98.245.67.65 (98.245.67.65)

 1  illuminati-130                                138.67.130.61
 2  138.67.63.253                                  138.67.63.253
 3  vermiculite                                  138.67.253.20
 4  csm-ct-gw                                      138.67.253.244
 5  138.67.253.2                                    138.67.253.2
 6  ge-7-24-ar01.denver.co.denver.comcast.net      68.86.128.17
 7  te-0-4-0-0-ar02.denver.co.denver.comcast.net    68.86.179.21
 8  te-9-3-ur01.wheatridge.co.denver.comcast.net    68.86.103.18
 9  *  *  *                                         {Times Out}

Now my guess is, whatever is sitting just beyond my router (what the modem connects to) is gumming things up. Even though the routes aren't EXACTLY the same, that appears to be the spot that the trace route either stops or doesn't get a response. My question is, for Comcast networks (particularly in Denver), what would be the device that typically sits there? Is there anything I can do about it?

That device seems to not respond to PING but does forward it along when I'm going outwards. But it looks like it eats it when the request is coming in. It's hard to prove that from these logs but I'm assuming that's the case because my router used to accept connections from the outside and I haven't changed anything on it.