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Sudden loss of internet won't stop inside company network

Posted on 2010-08-26
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Last Modified: 2013-11-16
here's the situation:
cable internet provider: cox
# of computers on network: 15+
network hardware: cox cable modem.  watchguard soho 6.4.x firebox/router.  20 port hub system, plus 4-port netgear hubs around the network.

wires going into watchguard router: 1 from cable modem.  1 from security camera dvr. 1 going to 20 port hub system.  1 going to computer station.

network has been running smoothly.  internet has been running smoothly for several years.  wed morning, we experienced an internet outage (but not network) that took about an hour for cox to figure out how to fix it.  after all the "it's not us.  looks fine on our end, etc etc." they fixed it by clearing the arp cache on the watchguard router and resetting the cable modem.  sometimes it took multiple tries.  in any case, the techs were always stumped as to what was going on.

then it happened again thurs morning.  again, same situation from the cox techs...bounced around, nobody could understand it.  clearing the arp cache worked again, but again took several attempts.

next it came back that afternoon.  same solution.  happened again that night and has not been fixed.

one cox tech suggested it could be because of some upstream frequency that was modified on wednesday, although he couldn't understand how it was related.

another interesting point: i could not access my watchguard router (via it's internal ip address) while the cox cable modem was online, but our internet was out.  on the flip side, i could access it as soon as my cable modem went down (and our internet was out)....i could also access it fine when both the cable modem and internet were up.


any ideas?????
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Question by:Bags305
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Expert Comment

by:rfc1180
ID: 33538764
1. Is the Cox modem in bridge mode rather than routed (Some Cable Modems offer a built in Firewall/NAT device).

2. Do you have a static IP or dynamic, if so, where the dynamic IP is configured could cause you some grief if the Cox cable had an issue where it locked up or had to be rebooted. What would happen is that when  the Cox modem received a new public IP, this could have caused traffic to just stop as the ARP entry on the Watchguard had old information and clearing ARP resolved the issue (It really just depends on how the network is configured and so fourth).

3. Is the watchguard a managed device from Cox? (If so,my recommendation would be to just stop, do not worry about it, it is their responsibility as the issue could be related to several issues and just guessing what the issue could be will just drive you up the wall [Maybe contact your Cox Account Manager and explain to them what is going on and you want the issues escalated [of course, assuming this is a business account]).

4.Do you have access the the Watchguard, if so, before you cleared arp, what did the arp table show?
5. Were you able to ping your ISP far end IP (This would be your default gateway).


Billy
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Author Comment

by:Bags305
ID: 33541931
1.  Yes.
2.  Static....but what you described is kind of what they described as solving the problem for the time being.
3.  It is a business account, but the watchguard is not provided by Cox, and they have told me they do not offer support on it.
4.  Access depends on the cable modem/internet and whether it is up/down...see original post.  Not sure about what the table showed, but I could ask next time - not sure where I would find that info in the Watchguard.
5.  Didn't try that.  I will let you know on next time.
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Expert Comment

by:dpk_wal
ID: 33544011
Earlier there used to be issue that if the internal network was infected with malware; this would cause all NAT ports in SOHO to get consumed causing internet inaccessibility.

Now I do not remember completely, but there is a hidden page where you can see the activity from your clients:
http://internal-ip/debug.htm
Here, if one of the machines is infected with malware you would see too many connections from it.

Removing the rouge machine from network would help; and rebooting just SOHO would free up all the NAT ports resuming internet connectivity right away.

Can you check if this is the issue and update.

Thank you.
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Accepted Solution

by:
Bags305 earned 0 total points
ID: 33561178
Cox readjusted some upstream frequency settings.  Apparently, they were not compatible with my Watchguard router and needed to be stabilized.  Haven't had internet loss since the change.  It took me several phone calls - some lengthy, some short - and about 6 different techs, before this was suggested.
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Expert Comment

by:dpk_wal
ID: 33563537
Good to know problem is resolved; thank you for update.
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