MN-100 LAN connectivity issue

Archived from groups: microsoft.public.broadbandnet.hardware (More info?)

We have an MN-100 base station that we've been using for many years now
that recently started acting strange. Without provocation, it
disconnected a local computer from the network, and will only allow it to
reconnect when the cable modem is unplugged.

Details as follows:

MN-100 serving two computers (sometimes more) in DHCP mode. Connected to
a cable modem upstream, again using DHCP. All computers running WinXP
SP2 (Home or Pro). Using default 192.168.2.* network, running TCP/IP
only.

One day, after a short break, a computer got cut off from the network (no
access to base station, LAN or Internet). Nothing was rebooted or
powered down during this break, and no software configuration changed.
Computer reported as "disconnected" from the LAN, and trying to repair
the connection failed to acquire an IP address. However, the appropriate
cable's light was lit on the base station and occasionally blinking.

Further investigation showed that unplugging the cable modem from the
base station would allow the computer to come onto the LAN and connect to
the base station and the other computer (but obviously not the Internet).
Reconnecting the cable modem immediately severed that computer's
connection.

Solutions attempted with no results:
- change network cable to affected computer
- plug cable into another port on the base station
- reset and power off all computers
- reset base station
- power off base station and cable modem
- check base station security settings (no MAC or client exclusions)
- change network to 192.168.5.*
- reset base station to default settings (firmware didn't reset though?)
- manually set computer's IP address, both inside and outside DHCP range
- unable to try connecting other computers (no spare machines)
- unable to try switching network adapters (all built-in, no spares)

Any ideas? At this point, I suspect a hardware failure (hopefully on the
base station, not the computer!) and will probably go out and buy a new
router tomorrow.

Thanks in advance for any help.