[PLUG] Router issues

[John Jason Jordan]

My home network is all cat6 wiring, including jacks and patch cables,
and both my laptop and my desktop are gigabit capable. I pay Comcast
for 50 Mbps which is fast enough that Ktorrent shows download speeds up
to 7 MB/s when I download a distro ISO. 

The network consists of a Motorola Surfboard SB-6121 modem (DOCSIS 3.0,
rated for about three times the speed I pay Comcast for), a D-Link
DGL-4100 router, connected to a Linksys WRT-G (only used for the
phone), and two gigabit rated 8-port switches. With the exception of my
phone, both computers (laptop and desktop), laser printers, and an
HDHomeRun TV tuner are connected by ethernet, although the laptop
simultaneously connects to the WRT-G.

About a month ago I was suddenly unable to connect to the internet.
Eventually I discovered that one of the two switches was unplugged from
the wall wart, probably thanks to the cat. But before discovering the
unplugged switch I tried numerous fixes, including swapping out the
DGL-4100 router (gigabit rated) for an older D-Link DI-604 (not
gigabit rated). When I finally discovered and fixed the unplugged switch
I just left the older DI-604 router connected.

Last week I downloaded the latest ISOs for a couple distros, and noted
that my download speed was only about 3.5 MBps, where it was usually
twice that. These ISOs usually have hundreds of seeders, so I always get
close to the maximum that I pay Comcast for. I also used Speedtest.net
to verify that my maximum download speed is now about 3.5 MBps. My
first paranoid thought was that Comcast was either back to throttling
torrents, or they were giving me only half the bandwidth I was paying
for. (The 50 Mbps is a recent upgrade from my previous 25 Mbps plan.)

I decided that the first thing I should do is swap the DI-604 router
back for the DGL-4100. After doing so I discovered that my network was
working perfectly, but I could not reach the internet. I tried the
usual troubleshooting procedures - power everything down and back up
again, one device at a time, swap cables, mutter expletives, etc.
Nothing worked. 

Eventually I decided to look at the admin page for the DGL-4100 using
Firefox from the laptop. But I could not get the page to load. Instead
I got:

	Please wait...
	The gateway is currently measuring your network connection.
	Accessing this web page might have an effect on the measurement.
	This page will refresh shortly.

After 10-15 minutes the login page suddenly appeared, but as soon as I
entered the username and password (both "admin"), the page would revert
to the above error message. I also tried it with Chrome, and from the
desktop as well, with the same results. Using my phone because I had no
internet connection to Comcast, I googled on the above error message. I
got half a dozen hits, but none of the suggested fixes resolved the
problem.

I also tried a hard reset on the DGL-4100, even though I knew that this
would wipe out the five reserved IP addresses that I had set up (for the
WRT-G, the HDHomeRun, the desktop computer, and two for the laptop -
but don't ask me why the laptop has two MAC addresses). However, the
reset accomplished nothing. 

By this time I had been muttering expletives to myself for over an
hour and was running out of fresh ones to use. So I decided to give up
on the DGL-4100 and go back to the DI-604, which had been working fine.
However, after reconnecting all the cables to the DI-604 and powering
it on I still could not get to the internet, although my own network
was working OK. 

However, unlike the DGL-4100, I was able to get into the web interface
for the DI-604. I reserved the five IP addresses as above, something I
had not bothered to do previously, and then renewed the lease.
Afterward I noted that ifconfig on the computers showed the new IP
addresses. But I still could not get to the internet. Eventually I
decided to reserve an IP address for the modem, something that I had
never done before for any router. The DI-604 had not automatically
detected the modem, but I was able to reserve an IP address for it by
manually entering its MAC address. And after renewing the leases again
I was finally back on the internet.

Here are some questions that I have for the network gurus here:

1) Does it make sense that my current lowered speed is because I am
using the older non-gigabit rated DI-604 router?

2) Why did reserving an IP address for the modem make any difference?

3) Has anyone had the above error message and, if so, how did you fix
the problem?

Other suggestions and observations welcome!