Over the last few months, I had been having sudden access losses while downloading files from the web. (Like long tracts from rec.crafts.metalworking.) The symptom is that things are going OK, and suddenly all access to the internet is lost. It just stops. No error messages save timeout. If one walks away and comes back an hour later, access is found to have been restored.
I called COMCAST Tech Support twice. The first time, they concluded that I had a bad cable modem, and had me replace it, although their remote diagnostics found no problem. The modem (a Motorola SB5100) is leased, so all this cost me was a trip to their office. However, problem not solved.
The second time, I called while access was stalled. Remote diagnostics again found no problem. This time, tried connecting the computer direct to the modem, without the Linksys BEFSR81B firewall/router: Access restored.
After a long wrangle about my use of static IP addresses in my local network (COMCAST only knows dynamic addresses), Tech Support came up with just one plausible and testable hypothesis, that the Linksys dropped the ball when a new DHCP address was provided by the modem. This was tested by manually requesting a new address, and proved not to be the case. However, I had some difficulty gaining admin access to the router, and the router had again forgotten its non-default password. Very odd.
I decided that I needed another router, if only to have the ability to do A-vs-B tests, and bought a NetGear RP614v4 firewall/router. This worked right out of the box, with factory-default settings, and downloads were quite a lot faster than before. Hmm.
What I think happened is that the Linksys router, installed in December
2000, was OK with the then download speeds, 1.5 mbits/sec max, but choked on today's speeds, at least 6 mbits/sec, with peaks to 12 or 15 if the ads are to be believed, and the jammed router was stumbling and getting confused.As for the wrangle about static addresses, in retrospect, I think I know the issue. COMCAST does not offer static IP addresses to home users, to prevent those home users from setting up web servers, and Tech Support has lots of canned responses to any mention of static addresses, and was having trouble understanding that this was different, that these static addresses were invisible outside of my local home network. (I use static addresses so devices that are powered up and down at random won't keep changing addresses.) I had to keep reminding them that static addresses were internet standards since the 1970s, predating DHCP by at least 20 years, and that yes COMCAST is expected to follow internet standards. They let slip that their database on me showed that "4 of 5 trouble calls from me were DHCP-related". The 1 of 5 will be when the original modem did in fact break. So, their fixation on static addresses blinded them.
Getting admin access to the brand new NetGear RP614 was a trip. The router kept trying to access a missing URL at Netgear. The available documentation was useless, and I had to call NetGear to learn the magic words to bypass this behaviour. This approach has to be costing them a lot - a call should not have been required. The router cost ~$70 at retail, and the average tech support call costs $30 or $40, so they probably have already lost money on this sale. Nor is it a good idea to depend on a URL for anything - they are far too short-lived.
Joe Gwinn