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TOPIC: Gateway not reachable

Gateway not reachable 11 years 5 months ago #9050

  • roticv
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Hello,

I think this site is full of information and full of experts. Anyway, I have a little question that has always been bugging me and irritating me to bits.

I have a NAT-router (of unknown brand) and sometimes I have problems connecting to the internet. This happens when I just switched my connection for like 30mins and it is extremely irritating. I know that I am still connected to the internet, because the light on my adsl modem says that it is connected.

However, when I open my browser, it would say "Looking up www.google.com" (google is my home page) or "Connecting to www.google.com". Sometimes, while I am surfing, I would get "Waiting for some url" for an extremely long period of time, before getting the error "Cannot connect to some url".

Usually when such things happen I would check my router login page. I would then see the words "Gateway unreachable" blinking. I can also see packets being sent, but no packets received.

So here's my question, is it my ISP's fault or my router's fault?
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Re: Gateway not reachable 11 years 5 months ago #9052

  • eddydreni
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Seems like either your router keeps resetting itself or something is happening when you do something to it.

When I had a router (Pine), everytime I mass pinged IP's, it would give me the same problem you have. I would have unplug the power of the router and plug it back in.

The problem was, the router was overflowing with ICMP commands and it couldn't handle all those commands at once. So it shut any incoming or outgoing connections down. I ended up replacing the router and everything was alright.

So, try mass pinging some IP's and see if it happens to you. If you still can't figure out whats happening, try just hooking your Modem to your Desktop machine.

Then subtract any possible problems. Best solution is to get a D-Link router (Yes, they cost a bit more, but believe me, you won't have any problems with them and the admin panel's of most D-Link's contain advanced features)
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ADSL 11 years 5 months ago #9054

  • TheBishop
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Hi roticv
I agree it could well be your router, but there is a chance also that it could be your ISP. The green light on your DSL modem/router shows that you have a fully negotiated DSL connection to the box in your local exchange. That doesn't mean however that your ISP is providing a valid internet connection on the end of it. Try eddydreni's suggestions and if things get no better you might need to take this up with your provider. Bear in mind though that they don't offer guaranteed unbroken service - I have ADSL from BT and they yank it for thirty seconds or so whenever they feel like it, usually early morning or late at night but more often than not when I'm using it!
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Re: Gateway not reachable 11 years 5 months ago #9057

  • roticv
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Thanks for your replies. So I guess that my router is at fault, but it seems to be able to heal itself - after a while, it would fix the "Gateway unreachable" problem. Anyway, my ISP is not a saint. There are quite a number of times that I lost connection and I am forced to reboot my router.

Just a question, how do you mass ping? I'm curious to find out what's the exact problem with my router.
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Re: Gateway not reachable 11 years 5 months ago #9059

I had similar problems with a zyxel adsl modem/router, it would lose connection now and then and i after i reset it it worked fine. In the beginning i thought it was the ISP's fault but after changing the modem/router (with an alcatel speedtouch) i have no problems at all. The link is always on and in te last 3 months i lost connection for just a couple of times.
Cheers,
PS. to mass ping from windows ping -t IP address
or just ping from linux
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Re: Gateway not reachable 11 years 5 months ago #9061

  • nske
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Yes cheap routers seem to freak out too easily. At first I simply had my Intracom router plugged in directly at a switch, which proved a bad idea: No matter whether I configured it to filter out the specific packets, it always seemed to flip out once some windows pc got infected with a worm that attempted to open an outstanding number of connection. I share my internet connection with too many people, most of them using Windows, so that was a very frequent problem. I ended up placing a P1 200MMX box with Openbsd as a firewall/router right in front of it, and all the problems disapeared (I am really curious how powerful the router's CPU is and how memory it has :)).

For such a low frequency, Bishop's suggestion sounds the most reasonable, however I suggest you also make sure your computer is not infected with any such worm, try a simple netstat -n in random times or leave a sniffer running for a while, when your connection is supposed to be idle.
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