network router problem

[Alphaflux]

ok i have a wireless rounter / 4 port switch hooked up to my cable modem witch gives internet access to my 2 laptops and my server rig in my house, the wireless connection uses 802.11b, and my comp is pluged directly into the router. now before i left for vacation everything was working flawlessly, before i left i shut off the router and all the computers leaving only the cable modem running, i came back 2 weeks later and now i have to reset the router constantly in order to restore internet access to all the computers. what the hell is goin on?! i have DHCP set up as i always have, it seems as though the router isn't picking up the IP address from the cable modem as it should be, and i must reset it to get it to work, i have tried 2 new routers of the same brand (linksys) and it hasn't fixed the problem, if anyone knows why this is happening any help would be appreciated, thanks

[phishphreek]

I have seen this problem from time to time. I installed a similar setup for one of my buddies.

I set his local IPs to static (instead of DHCP just because it is easy to keep track of 4 ips) and set the idle-timeout to 0. (idle-timeout may only apply to xDSL) also, make sure you're ISP can ping your router (allow ICMP on the firewall but restrict it to you're ISPs subnet(s) or DHCP servers)... because if they don't get a reply, they might issue that IP to another customer causing you to reboot router/renew your IP. You could also see if your ISP will assign you a static IP and that should solve it too.

[dcongram]

Losing ip address from cable modem(s) is common problem. It's the ISP / provider of the service.

Here....its an epidemic problem; and cable suppliers answer is "It has to be your computer; reboot or re-format" (hey won't fix the problem)

[gunit0072003]

You want to identify where the problem may be w/o guessing, rebooting or going out and buying a new router..Many at times people set up their networks w/o truly understanding how
and why things work the way they do..Just because something worked before and now it doesnt doesnt mean you may have set up your network up rite the first time..

You have a router with 2 interfaces (lets call them inside and outside)
inside is your private LAN protected and
outside is public interface unprotected (going to Cablemodem)

By the way,Cable modem is actually
a cable bridge. it is really a DTE device and a DCE device built in one..They refer to it as a modem instead as a bridge to simplify technology to average nontechnical user....

Your outside interface is set up as a dhcp client to grab an IP address from your cable carrier
and your inside interface is set up as a dhcp server to provide RFC1918 private addresses to your privaet LAN(PCs)

Now,
The problem may lie with one of the following:
1. Microsoft O/S, (bug w o/s etc...)
2. Wireless NIC cards (kit all together)
3. The router's DHCP service "craps out"
4. Your cable provider is not responding to your DHCP requests...
5. Last, check any default security settings on your router that
may be blocking ports, etc..
6. last, as this may seem obvious, check your speed and duplex settings..
avoid setting ur NIC settings to auto...(craps out sometimes)

Solution:
1. Perform an ipconfig /all on ur windows PCs (wireless and physical ones) to
determine if you are recieving an IP address from ur router.
Especially ur physically connected PC..It should atleast request an IP address.
2. console into your router and ping your default gateway (cableprovider) to see if u have
connectivity from your router out. Read the releas notes on ur router carefully for any
caveats known with OS.
3. last if you have access to, install a protocol analyzer and sniff network both on inside and outside of network to truly understand where problem may lie...( you can download free analyzer "Etherreeel" at http://www.ethereal.com/download.html.

Sorry for long response, Ild be interested in knowing what your test results were..

[Ghost_25inf]

sounds to me you need to ping your router if you get no reply its most likely the router another thing it could be is the modem but you would be able to tell that if the modem lights arnt lite right. One other posiblity is that the cable provider has gotten wise to your activities, meaning they want you to pay for each computer, so they could send a packet which resets the IP and in turns screws with the router. this can also be done by little script Kiddies wanting to get into your computer. Linksys routers are very good routers but yet they are known to take a crap every once and awhile, but not as much as you described. also Test the outlet not the right amount of power to the router can cause it to fail.

[VictorKaum]

Originally posted here by dcongram
Losing ip address from cable modem(s) is common problem. It's the ISP / provider of the service.

Here....its an epidemic problem; and cable suppliers answer is "It has to be your computer; reboot or re-format" (hey won't fix the problem)

Most ISP's do not support and some even do not allow LAN networks to be conencted trough a router with one IP adress (offcourse the majority of people does not care). Check the ISP's acceptable use policy, and it will probably state something that user routers or servers are forbidden. So it's not that strange that they don't give support for this kind of setup. Next, most ISP's with dynamic ip's for the customers do a refresh about every 24 or 36 or 48 hours. Like said before, it is possible that if a ping is impossible your dhcp lease expires and probably the ip will be assigned to somebody else.

[dcongram]

VictorKaum......very valid point. 'Our' DSL / Cable isp's now sell Router/Firewall which makes it acceptable/usage. They are trying to stop 'zombie' 'smurf' etc.

Their Help Desk will ask the client to plug a computer directly into the DSL/Cable modem for testing purposes. IP address will stay for a few minutes....then releases. (Same Help Desk answer - Reboot or Re-Format) Help Desk are not trained personnel.

After dealing with the Cable supplier (many occasions & locations) they have very POOR service. Other locations in North America may be better....but not 'here'. Cable internet supplier is notorious for poor service.

[gunit0072003]

To further add to VictorKaum's response about dynamic addresses provided by ISPs

He is right, ISPs will refresh the IP every so often, sometimes with same address other times with different one...

Now here is what you want to know about you router to determine if its an issue with you or not.

Your router is obviously doing atleast two things.
1. It's outside NIC/interface acts like a dhcp client to grab an IP from ISP
2. It the does whats called PAT (port address translation) to pat all your
private IP addresses to the public address received via DHCP/

Now you want to know, is your router smart enough to dynamically
PAT your private addresses to the newly recieved DHCP address it so often
renews from you ISP.. (info should be provided by router documentation)

[Alphaflux]

wow thanks guys, after reading through all that, i think i can fix it now, i'll post later and let you know what happens..