Strange network issue - webpages randomly stop loading

[Dr Girlfriend]

It's an issue that has been plaguing me for months, originally thought is was an issue with the ISP, but today I discovered I could fix it by unplugging the router attached to the ADSL modem.

The issue is that at random times during the day, I suddenly stop being able to load pages, and chrome will kick up "DNS_ERROR_CONNECTION_NOT_FOUND", or "Webpage took too long to respond". There are a number of error messages. Anything connected via IP stays connected most of the time. Sometimes it will fix itself, sometimes I can reboot the modem. But it can always be fixed by unplugging the attached router.

The ADSL modem is an Actiontec F2250 (has been replaced twice by the ISP techs), and the two wireless routers I've tried are a linksys DIR-628 and an apple airport extreme.

Any thoughts on what could possibly be causing this?

 

[DeadlyDays]

Your ISP's DNS server. I don't know how long your IP lease times are, but let yourself get an IP address from the modem on the router, copy the information. Then change your router to static IP, put the information in and set the primary DNS server to a public address and see how long that works.

EDIT
Not to say 100% that is your problem, but I had a problem with MY ISP having DNS issues for a long time(and then after that DHCP Issues) And this work for me for entire lease period after constant DNS issues.

 

[Solandri]

Try setting the router to use 8.8.8.8, 8.8.4.4 (Google) and 208.67.222.222 (OpenDNS) as DNS servers.

If you leave it on Auto, it'll use the ISP's DNS server. Unfortunately, ISPs like to play all sorts of games with their own DNS servers, to make some advertising revenue when you make a typo in a domain name. This makes it extremely difficult to diagnose DNS problems, because what should be a DNS failure ends up being returned as a legit page.

 

[Dr Girlfriend]

That was actually my first step months ago. I have the modems DNS servers set to OpenDNS, and when that failed I tried Google DNS. Also tried setting DNS locally on my computer, which also didn't fix it. There is some weird interaction going on between the router and modem that's causing problems for even devices that are hard lined directly to the modem.

Like I said, unplugging the router resolves the problem instantly (literally the second I pull the plug, everything starts working again), so actual DNS server problems don't seem to be the issue.

 

[DeadlyDays]

If you are directly connection personal machines to the modem(company modem?), AND experience this issue across all personal devices that you connect to the modem(more than one). Then this is something you should call the ISP on and report(though they'll make you do some silly troubleshooting steps just in case you are silly). They might not do anything on it, but who knows sometimes you get lucky.

EDIT
if setting your own DNS not working in any setup, then issue is pointing to your own system and this not being an ISP issue or a router issue. Though you never know, could still be ISP and some sort of routing issue or configuration issue in their system.

 

[Dr Girlfriend]

If you are directly connection personal machines to the modem(company modem?), AND experience this issue across all personal devices that you connect to the modem(more than one). Then this is something you should call the ISP on and report(though they'll make you do some silly troubleshooting steps just in case you are silly). They might not do anything on it, but who knows sometimes you get lucky.

It's not something they can fix, I've had techs out and their first step is to unplug everything but one ethernet connected computer that's connected to the modem, and check the line. It's always good (because the router is disconnected). Every time they say there's nothing they can do. And rightfully so.

That's why I came here, because I cannot for the life of me figure out why having a router connected to the modem would cause this issue.


EDIT: it does happen on every computer in the house, doesn't matter if they're on the router wifi or connected directly to the modem.

 

[DeadlyDays]

sorry, didn't see rewrite. So if you have router set to DHCP for WAN connection, and use the internal DHCP service for LAN site and connect personal machines using DHCP you get this issue right? Do you also get this issue with static addresses set as well?

I am thinking further on this but clarification of above may help.

EDIT, and by directly connected to modem you mean connected to the router? am I misunderstanding something, how are you having router connected AND computers to modem. Is this a Router/Modem combo device with a personal router plugged in?

 

[Solandri]

1. Try changing the cable between the modem and router.

2. When you connect your computer directly to the Actiontec modem, what IP address does it get? From a Google search, the Actiontec F2250 looks like a combo modem/router. If its LAN IP address range is the same as your router's LAN IP address range, that will cause all sorts of random problems. e.g. If your computer's IP when connected to your Linksys is 192.168.1.x, and when you connect the computer to the Actiontec it's 192.168.1.x, that's bad. You need to change the IP address range of either the Linksys or the Actiontec.

If 2 was in fact the problem, I'd also assign your Linksys a static IP address on the WAN port (within the Actiontec's LAN IP range), then configure the Actiontec's DMZ to that static IP address.

 

[Dr Girlfriend]

sorry, didn't see rewrite. So if you have router set to DHCP for WAN connection, and use the internal DHCP service for LAN site and connect personal machines using DHCP you get this issue right? Do you also get this issue with static addresses set as well?

I am thinking further on this but clarification of above may help.

The router is currently in bridged mode (Airport extreme). The linksys didn't have a bridge mode and distributed its own IPs. Same issue with both. The modem is a wifi/modem combo and has its own DHCP server as well (reason I have a router is to have Internet/wifi in another building, the modem and router are connected by ethernet) . This is where I start getting out of my networking knowledge depth, hopefully that answered the question.

 

[DeadlyDays]

This is where we are getting our issue then, makes more sense now(and slightly more tricky to TS).

EDIT sorry I am editing so much, only 5 hours of sleep and at end of day. I will think a bit harder.

 

[Solandri]

The router is currently in bridged mode (Airport extreme). The linksys distributed its own IPs. Same issue with both. The modem is a wifi/modem combo and has its own DHCP server as well (reason I have a router is to have Internet/wifi in another building, the modem and router are connected by ethernet) . This is where I start getting out of my networking knowledge depth, hopefully that answered the question.

Wait wait wait. Which port on the Linksys is plugged into the Actiontec modem? If you're plugging a LAN port on the Linksys into a LAN port on the Actiontec, then you have two DHCP servers which will cause exactly the problem you describe.

The cable needs to go from the LAN port on the Actiontec to the WAN port on the Linksys. (The Airport could cause a similar problem, but I'm assuming it's smart enough in bridged mode to turn off its own DHCP. You might want to try unplugging it while you diagnose the problem with the Linksys and Actiontec.)

 

[Dr Girlfriend]

This is where we are getting our issue then, makes more sense now(and slightly more tricky to TS). Is it a wireless or wired bridge between the routers, and do you have DHCP disable on your bridged router?

Wired, 80ft CAT6e cable. In the airport utility there's simply the option to place it in bridge mode, no DHCP settings I can see unless I change it out of bridged mode and into "Distribute a range of IP addresses mode".

 

[Dr Girlfriend]

The router is currently in bridged mode (Airport extreme). The linksys distributed its own IPs. Same issue with both. The modem is a wifi/modem combo and has its own DHCP server as well (reason I have a router is to have Internet/wifi in another building, the modem and router are connected by ethernet) . This is where I start getting out of my networking knowledge depth, hopefully that answered the question.

Wait wait wait. Which port on the Linksys is plugged into the Actiontec modem? If you're plugging a LAN port on the Linksys into a LAN port on the Actiontec, then you have two DHCP servers which will cause exactly the problem you describe.

The cable needs to go from the LAN port on the Actiontec to the WAN port on the Linksys. (The Airport could cause a similar problem, but I'm assuming it's smart enough in bridged mode to turn off its own DHCP. You might want to try unplugging it while you diagnose the problem with the Linksys and Actiontec.)

I double checked, and it is modem LAN to router WAN. The linksys isn't being used, was only used for a bit to try and eliminate a flat out bad router.

 

[DeadlyDays]

If you have the modem/router act as a router and leave DHCP enabled on it(so its default state). It is easiest, and works the best, to disable DHCP on your personal router, set your personal routers LAN address to the same subnet as the combo device, and ignore the WAN port thus avoiding any doubleNAT issues. No bridge needed, the second router acts like a wireless switch(if it is a wired connection between the combo and the router as I am understanding it).

By same subnet I mean the first 3 numbers in the IP address on the internal network. So typically 192.168.1.X or 192.168.0.X The Primary router will always be at X.X.X.1 on the internal network, so set the second at X.X.X.2 for the internal webpage.

 

[Dr Girlfriend]

If you have the modem/router act as a router and leave DHCP enabled on it(so its default state). It is easiest, and works the best, to disable DHCP on your personal router, set your personal routers LAN address to the same subnet as the combo device, and ignore the WAN port thus avoiding any doubleNAT issues. No bridge needed, the second router acts like a wireless switch(if it is a wired connection between the combo and the router as I am understanding it).

By same subnet I mean the first 3 numbers in the IP address on the internal network. So typically 192.168.1.X or 192.168.0.X The Primary router will always be at X.X.X.1 on the internal network, so set the second at X.X.X.2 for the internal webpage.

The airport extreme doesn't have a way to set it's own LAN IP (no clue why not). But would connecting from modem LAN to router LAN (instead of WAN) with the router in bridged do the trick?

I set it up that way above minute ago, and the airport has an IP assigned in the modems subnet (looking at the modems config page > connected devices), and the internet is working so far. With it being random though it's a pain to trouble shoot and call it fixed until a day or two passes.


EDIT: spoke too soon, the internet worked for a minute after setting it up that way, then went right back to not working.

EDIT 2: Swapped the airport out for the linksys and set it up as you described, everything has been working for the last little bit, so fingers crossed.

 

[Solandri]

If you have the modem/router act as a router and leave DHCP enabled on it(so its default state). It is easiest, and works the best, to disable DHCP on your personal router, set your personal routers LAN address to the same subnet as the combo device, and ignore the WAN port thus avoiding any doubleNAT issues.

I was assuming OP wanted the double NAT because Actiontec routers are a pain to setup and configure. Their menus are unintuitive, with features buried in areas where you least expect to find them. I was stuck with an Actiontec modem/router by my ISP, and after months of frustration just bought a Linksys router and set it up as DMZ on the Actiontec to avoid the double-NAT problem (took me a good 15 minutes to find the DMZ option on the Actiontec). From speaking with others, I am not alone.

EDIT 2: Swapped the airport out for the linksys and set it up as you described, everything has been working for the last little bit, so fingers crossed.

Yeah, I was beginning to suspect the Airport was adding a second DHCP server and was gonna suggest eliminating it from your setup for a day to see if the problem goes away. Bridge mode is supposed to disable it, but I've never really trusted how Apple hides stuff like this under a pretty UI.

 

[Dr Girlfriend]

Everything has been running stable for a few days now. Thanks all for the help!