I don't, because I fear other can if I set it to do so. Have you double checked your router to see if anything got changed? You might try power-cycling the router or even restoring the default settings and reconfiguring it.
No, Comcast doesn't prevent port 8080 access. At least it doesn't in this area. I'd check your router settings, sounds like your external access setting is turned off. Have you made any firewall or port forwarding changes lately?
Where are you accessing the router from? Many ISP's and work locations limit what ports you can use.
The access is definitely turned on. I even turned it off, saved it, then turned it back on again.
No firewall changes lately other than spy ware stuff, but even then, I'm not trying to access my computer, just direct to the router.
I even tried to access the router via it's WAN IP from my computer using Comcast locally and same thing. I normally access it from work who we're connected with a fT1 from Bell. I am the admin for the work system, so no changes there.
ping uses a different IP protocol than TCP, which is what HTTP uses. Sure sounds to me like somoene's blocking. There's only so many points along the way that can be doing it. The router, Comcast, the local ISP, and work environment. But if you elimiate each as a source of the problem, then your problem must lie elsewhere.
A good test is to try hitting the router from the outside using a system on Comcast and see if that works. Also, try putting a hub/switch in front of the router and using a computer connected to the hub. These will tell you whether the probem is with Comcast or the router, but if it works, then the block is upstream somewhere.
ping uses ICMP already, that's the IP protocol it uses to do it's job. Some versions of ping have added the use of other protocols (such as TCP), but these are very nonstandard and specific to each tool, and they usefulness is limited.