Sounds like a router problem more than an ISP problem then.
I am using a Dynex router and do not have to do any of those things to allow an outside access to different ports on the computers I have hooked up to it.
With Dynex router I access it with my browser and it shows me all of the computers connected to it. I click on the one I want and then a list of ports is displayed and I can check the ones I want open for that computer. I don't have to do anything else. I have found the Dynex routers are sweet to use and have some of the best builtin user control software. They beat Lynksys hands down for ease of use and configurability. Plus they are alot cheaper.