[fivehands]

I have an eircom zyxell modem (p660hw t1 v3) with two pcs running Windows 7, connected via cat5,( we will call those connection 1 and 2 for future ref), and then another 20m+ cat5 running from that modem, going to a linskeys e1000 router in another building for wifi over there. We will call that connection 3.
All worked fine for ages, but recently the internet connection to 1 and 2 is intermittent when connection 3 is plugged into the zyxell, even though it is perfect when used on ipad over wifi.
I will still get wifi inet connection from the zyxell on an ipad, and on a laptop connected via cat5, at the time when the two pcs have none.
When I unplug connection 3(Going to the linskeys) from the zyxell, everything works again.
Sometimes it all works with connection 3 plugged in. Then all of a sudden it will display the page not found message below



It is mostly connection 2 that displays the message below



The server at www.******.com can't be found because the DNS look-up failed. DNS is the network service that translates a website's name to its Internet address. This error is most often caused by having no connection to the Internet or a misconfigured network. It can also be caused by an unresponsive DNS server or a firewall preventing Google Chrome from accessing the network.
Here are some suggestions:
Reload this web page later.
Check your Internet connection. Reboot any routers, modems or other network devices that you may be using.
Check your DNS settings. Contact your network administrator if you're not sure what this means.
Try disabling network prediction by following these steps: Go to Spanner menu > Options > Under the Bonnet and deselect "Predict network actions to improve page load performance." If this does not resolve the issue, we recommend selecting this option again for improved performance.
Add Google Chrome as a permitted programme in your firewall or antivirus software's settings. If it is already a permitted programme, try deleting it from the list of permitted programmes and adding it again.
If you use a proxy server, check your proxy settings or contact your network administrator to make sure that the proxy server is working. If you don't believe you should be using a proxy server, adjust your proxy settings: Go to the spanner menu > Options > Under the Bonnet > Change proxy settings... > LAN Settings and deselect the "Use a proxy server for your LAN" checkbox.
Error 105 (net::ERR_NAME_NOT_RESOLVED): Unable to resolve the server's DNS address.





I have changed all cat5 cables even though it would be highly unlikely that both cables to pc 1 and 2 would be faulty.
I have reset and rebooted both modem and router many times.
I have rang the ISP and they have tested the line and found it to be 100%.
What could be causing this please?
Could it be the zyxell modem?

[risingphoenix1985]

Hello,

It does sound like the Zyxell is the cause of this problem.

When you say you did a reset the device, how did you do it? Did you press the reset button or do it through the web interface?

When you log on to the Zyxell, can you see any settings for your DNS?

[fivehands]

Hi

I pressed the reset button yes.
And yes, I can see these

First DNS: 89.19.64.36(ns1.vodafone.ie)
Secondary DNS: 89.19.64.164(ns2.vodafone.ie)
Tertiary DNS: 0.0.0.0

[risingphoenix1985]

Hello,

Can you change them? If so, just to test my theory could you set the following...

Primary 8.8.8.8
Secondary 8.8.4.4

The above are for Google DNS. I just want to see if switching to another DNS service will fix the problem. If this doesn't work, let me know and we can try a couple more things.

[fivehands]

Hi

Tried that, but unfortunately made no difference

Now connection 1 and 2 work regardless of wether 3 is plugged in but 3 wont work at all...
Yesterday 3 would work if plugged in, but 1 and 2 would go off...

it's all getting stranger and starnger!

I might try replacing both modem and router one by one and see what happens
What you think?

[risingphoenix1985]

That is strange can you try the following...

Open the command prompt on your PC (Start->Run->cmd) and type ipconfig /flushdns
This will clear you DNS cache.

Next, can you type tracert www.google.com This will print out all the hops your connection takes to the server. Let me know what it says.

[fivehands]

All done...

One from both pc's...

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[risingphoenix1985]

Hello,

Those screenshots look perfect in that the commands worked fine with no errors (not what I was expecting).

The only other thing that I can think would be causing this problem would be an IP address conflict.

On your 2 Windows 7 boxes can you open your network settings and locate the adapter you are using. (Network and Sharing Center -> Change adapter settings) Right click it and select properties.
In the list find "Internet Protocol Version X (TCP/IPvX)" where X is either a 4 or a 6. Select these individually and click the "Properties" button.
Are both the Boxes set to "Obtain an IP address automatically"?

Can you get the IP address on your Windows boxes? the quickest way would be to get the command prompt open and type ipconfig

Make a note of these and then turn on the iPad. Once the iPad has connected get the IP address of it and see if it matches one of your Windows boxes.

[fivehands]

How do I get the ip address on the ipad?

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[risingphoenix1985]

That's good, so you have the following...

PC1 = 192.168.1.2
PC2 = 192.168.1.3

Which is completely fine. It's been a while since I played with an Apple device, but if memory serves me you should be able to get the IP by clicking settings then wi-fi or wireless (I forget which) click on your network and expand it which will tell you the IP.

[fivehands]

Hi

Ok, this is all a bit weird from the start we know, but weirder still is, that everything seems to have started working not just perfectly with all 3 connections plugged in, but faster operating and internet speeds too it seems.

Could the dns change that you suggested have taken a little time to 'kick in' as it were, or does that usually take effect immediately? I didn't change it back to the default settings after you asked me to enter your ones.

If the latter is the answer, then I don't know how, or why, but it's all ok again.
Arn't computers just great?

Hey, it seems I've kinda wasted your time at this point and I'm sorry for that, but thanks ever so much for taking the time to try and sort it. You actually may have done by doing some of the stuff we did. I don't think we will ever know, unless you have an answer? lol.

Anyway, it may all go off again tomorrow and if it does I will troubleshoot it step by step with all the components. Do you think the modem is probably on the way out or could it have been something else?

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[risingphoenix1985]

Hello,

They do say that DNS changes can take up to 72 hours in the most extreme of cases but normally they tend to take effect within 3 minutes.

I honestly thought you had an IP address conflict in that when you turned on your iPad it would ask for an IP and get one that was in use by PC1 or PC2.

You say that it is going faster, changing your DNS provider should in theory reduce look up times so I'd say there was a 65% or so chance that the DNS change has fixed your problem but if that's the case I am very surprised indeed that it would have taken this long to kick in.

Another possibility would be that your ISP has maybe fixed something on their side.

Either way, it works; fantastic news. Hope it doesn't break again, but if it does you know where to find me.

[fivehands]

Hi
Back again!

So, it all stopped working a few days after that and went back to being intermittent.
After many 'Nige to Vodafone' calls, and testing lines again (which showed faults by vodafone but never any by eircom when the engineers were sent out)...., I then got fed up and swapped the two modems round and placed a new vodafone modem they sent me, at the point where the line enters the house, done away with the extension, and hard wired the cat 5 underground direct to PC 1 and 2, my printer on the network and the cisco router, for wifi round the office.
Still intermittent. Couldn't believe it, but now when I troubleshoot one by one and unplug only the cisco, everything works.

My question now is, could the cisco be conflicting with the vodafone? It wasnt before with the eircom for sure because I tested it in out out before going to the bother of digging up ground and hardwiring.
Are there any settings/channels that should be checked?

[risingphoenix1985]

Hello,

It certainly does sound like your Cisco box is causing trouble. However, If you haven't changed anything and you suddenly went back to intermittent connection I would think your ISP has done something.

The only things to check on the routers that you have is which one (possibly both) is assigning IP addresses using DHCP on your network.

[fivehands]

Hi
Sorry it's taken so long to reply, I have just been working away with the cisco unplugged, without any drop in internet since our last post so it's definitely the problem.
I actually plugged it in this morning just to see and lo and behold I lost connection within 10 mins or so. First time in a few weeks.

What I would like to ask now, is if there is a way to stop this conflict and get my Cisco router working so I can have WiFi in the office area too? I am unsure of how to check which one is assigning IP addresses using DHCP on the network, or any other settings or channels that may need changing.

Just to recap, I now have a Vodafone modem in the house at the phone line entry point, with 4 Ethernet cables hard-wired to the office across the street. ( I have since learnt that I could have just used a switch?)

Anyway....

1 goes to pc1, 1 to pc2, one to my network printer. All working great. When I plug the 4th one into a cisco router, all goes down intermittently.... (And sometimes, my iPhone will work great on WiFi in the office whilst the pc's are both still down!) Grrrrrrrrr!!!

What settings can I check or change to get it working....!
Thanks!