PC regularly loses internet access on wired network

[Todd]

This problem has been ongoing and I have exhausted my solutions to fix
it. Here goes:

3 PC's are on an internal 10/100 wired network using a Linksys router
and CAT6 cabling. They all use Win XP SP1 on Pentium 4 systems. Two of
the systems work fine. The third system gets its Internet access cut off
on a regular basis. The easiest method for getting the system back on
the Internet is to run the "IP config" command with release/renew.
However, when the system loses its Internet connection it still has
connectivity on the LAN. You can share files, see other network devices,
and even use printers. Just the Internet access is cut. No browser use
or e-mail. One item to note: when I use a command prompt and ping the
router I get the response "Destination specified is invalid." This is
consistent when the system loses internet access.
I have checked all the physical items such as cabling, the router, and
the system itself. Nothing seems to make any difference. I have tried
changing timeout periods on the router as well as the MTU values. It
just doesn't make any sense! A service company even ran diagnostics on
the machine for two days straight. No problems found (though I don't
always believe that 100%).

If anyone has any ideas I would greatly appreciate it! In all the years
I have done IT work this is one of the strangest situations I've come
across.

Thanks in advance

Todd

 

[johnsuth]

This problem has been ongoing and I have exhausted my solutions to fix
it. Here goes:

3 PC's are on an internal 10/100 wired network using a Linksys router
and CAT6 cabling. They all use Win XP SP1 on Pentium 4 systems. Two of
the systems work fine. The third system gets its Internet access cut off
on a regular basis. The easiest method for getting the system back on
the Internet is to run the "IP config" command with release/renew.

Are you losing your DHCP lease?
I use static IP so I don't have that problem or know the solution.
Have you tried static IP?

However, when the system loses its Internet connection it still has
connectivity on the LAN. You can share files, see other network devices,
and even use printers.

File and device sharing is a function of Netbios. It has nothing to
do with internetworking. There is nothing mysterious about file sharing
still working.


Just the Internet access is cut. No browser use

 

[Kurt]

File and device sharing is a function of Netbios. It has nothing to

do with internetworking.

Well, yes and no. If the transport for netbios is tcp, then it shows that
the TCP/IP stack is at least functional at the local subnet level. When you
ping the router (I'm assuming its local IP address), "Destination specified
is invalid." message is unusual. If you mean it's public address, thatt
means there is no default route. When you do a "route print" from the
command line when it's not working, where does the entry for 0.0.0.0 point?
If it's missing or incorrect, I's suspect some kind of spyware/hijack type
something trying to mess with your sockets or tcp stack.

....kurt

 

[Todd]

Are you losing your DHCP lease?
I use static IP so I don't have that problem or know the solution.
Have you tried static IP?




File and device sharing is a function of Netbios. It has nothing to
do with internetworking. There is nothing mysterious about file sharing
still working.


Just the Internet access is cut. No browser use

Sorry for the reply delay.... Been out...

To answer your questions:

Yes, I did try using a static address and it didn't make any difference.

As for the netbios item: I only mentioned it as an example that the
hardware devices and wiring were making a connection. I understand that
it is separate from the TCP issue. To add more details, I can ping the
IP address of the other systems that are online at the moment with no
problem (including the gateway). Just nothing beyond the gateway. I also
cut and crimped on new connectors for the wiring.

Todd

 

[Todd]

Well, yes and no. If the transport for netbios is tcp, then it shows that
the TCP/IP stack is at least functional at the local subnet level. When you
ping the router (I'm assuming its local IP address), "Destination specified
is invalid." message is unusual. If you mean it's public address, thatt
means there is no default route. When you do a "route print" from the
command line when it's not working, where does the entry for 0.0.0.0 point?
If it's missing or incorrect, I's suspect some kind of spyware/hijack type
something trying to mess with your sockets or tcp stack.

...kurt

I'll check the "route print" information. That's one item I haven't
tried. I was also thinking of setting up a console (MMC) to log traffic
activity within the PC itself in hopes I might find something unusual
when the "disconnect" actually occurs. I am not exactly sure what
entries would work. Any ideas on this?

Todd

 

[Todd]

Sorry for the reply delay.... Been out...

To answer your questions:

Yes, I did try using a static address and it didn't make any difference.

As for the netbios item: I only mentioned it as an example that the
hardware devices and wiring were making a connection. I understand that
it is separate from the TCP issue. To add more details, I can ping the
IP address of the other systems that are online at the moment with no
problem (including the gateway). Just nothing beyond the gateway. I also
cut and crimped on new connectors for the wiring.

Todd

Ooops! My mistake in the reply:

Pinging the other systems on the network works. Pinging the router gives
me the "Destination specified is invalid." response.

Todd

 

[johnsuth]

I'll check the "route print" information. That's one item I haven't
tried. I was also thinking of setting up a console (MMC) to log traffic
activity within the PC itself in hopes I might find something unusual
when the "disconnect" actually occurs. I am not exactly sure what
entries would work. Any ideas on this?

It seems logical that malicious software would cut your default route
and thus internet access. I would expect ipconfig to refresh the
routing table and put you back on air.