Router error

Hi All,

I need your help please.
I have a router type PT-link WR741ND v4
I am suffering from Wifi breakdowns with this router and I just cannot figure out what could cause this error.
I am using WPA/WPA2 personal with automatic version and encryption (i have checked, the router uses WPA2-Personal + AES encryption)
Group key update period has been set to "0" and my password contains letters and numbers too and it is more than 10 charcters.
While the wifi refuses to forward internet to users the cable connected part is still working properly
Sometimes it works for days sometimes it is breaking down twice per day.

Help me please solve this issue.
Thanks in advance.
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Reset your Router using a paper clip and press the small button in the back of the router

then configure it after you press the reset button
agriboy1980Author Commented:
I did that already, and I still have the error.

Even I have already updated it to latest firmware.

Didn't help.
What kind of connection is your internet, cable or DSL?  How many users are connection through your wireless?
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Good Day

I don't have specifics like what operating system you are using,but i will try help none the less

I came across the same problem in the past and this is what i did,first of all some time's the
the security is what causes the problem,so what i did was manually setup the wireless network ,and then disable the SSID from broadcasting , on Security type you choose : No authentication (Open). And on encryption you can choose the AES option or just leave it to whatever defaults it gives you.
Just REMEMBER to disable your SSID so that no one else can pick up your network here is a link to help:

agriboy1980Author Commented:
It is cable internet. There are like 5-6 users connecting to this wireless.

I had an idea that maybe the group key period should be changed?
Interestingly, the Group Key Update Period defaults to 0 which means that the group keys aren’t rotated.  Since rotation of keys is a key element in wireless security it should default to something greater than 0.  Some routers that I’ve seen use a key rotation period of 3600 seconds.

I found the info on this link :

the wifi refuses to forward internet to users

do you loose the wifi connection altogether or just internet access ? can you still ping the router when it happens ?

if the wifi connection dies, it may be due to external interference. changing channels might help.

if the wifi is up, the router pingable and you have no internet access, then we need to dig into the router's internals
Fred MarshallPrincipalCommented:
You should probably also consider that the router is flaky.
Presumably a router reboot doesn't fix the problem?

You might reinstall the router firmware before replacing the router.
agriboy1980Author Commented:
The router somehow doesn't forward internet to users via WIFI but it still operates normal on the cable side and is pingable, reachable.
After I restart it everything is going back to normal and it works on  wireless and cable.
Although there are a lot of wireless routers present near to mine because there is a block of flat on the opposite side of my building.
Earlier I used a much older TP-link router and this kind of issue has never happened.
I am clueless.
my (originally unclear) question is : is it pingable by wifi users ? do the users loose the wifi connection altogether or do they have a working wifi connection but no internet access ?

also, do all the wifi users experience the same problem at the same time or do each of them seem to loose their connections randomly ?
Fred MarshallPrincipalCommented:
It sounds like the router is losing DNS service on the wireless side only.  That seems unusual as I believe that the DNS service is likely to come from the same "function" within the box (no matter the connection to the internal switch).

You can test this theory easily:
On a wireless client, open a command line window and type:
nslookup <Enter>
this should result in the IP address of the DNS server and should likely be the LAN IP address of the router.

Do the same on a working/wired computer.  Is there a difference?
What are the results?

I presume there are no separate settings for DNS on the router BUT:
How are you getting DNS on the wired computers?
- are their IP addresses (which would include DNS) entered manually / static?
- are their IP addresses obtained "automatically"? i.e. via DHCP from the router?

How does this compare with the wireless client setup?

What happens if you set a wireless client manually?  Does the failure persist or does it go away?
[I would enter a number of DNS addresses including: the router, the gateway if it's a DNS server itself, an ISP DNS address, a "public" DNS address like:,,,, etc.]

If DNS is working via DHCP then I guess you wouldn't have asked this question :-).
If DNS is working using static addresses either wired or wireless then at least you have a method that works.
If DNS is not working via DHCP but only on wireless then I would:
- Look for a setting in the router that would affect the wireless clients only.  Maybe a DHCP setting (Enable/Disable) just for wireless.  Maybe that "bit" is switching / resetting.
- What happens if you reboot the router and do nothing else other than on a wireless client do this:
- ipconfig release
- ipconfig renew

I'm still thinking that a flaky router is a possibility.  Have you tried another one?
dns config problems don't seem to fit if only part of the clients loose their connectivity randomly. there is definitely a single DNS server on any such small router. if the problem was a faulty external server, rebooting the router would not solve the problem.

i assume the adresses are obtained through dhcp and both the wifi and wired users receive the box's address as their primary dns server ?

when the problem occurs, if pinging the router still works, the output of a traceroute/tracert to whatever external address would be welcome (use for example)

if pinging the router does not, can existing or new clients obtain a new wifi connection ? what happens if you try to manually connect a new client ? do you still see the network SSID in the list of available networks ?
Fred MarshallPrincipalCommented:
I have found that using logic to figure out what's going on with flaky routers can be mind-boggling.  That's because the behavior can't be explained.  So, one can go in circles with troubleshooting and never get anywhere really.

Example: Flaky router will allow you to open some web pages and not others.
In this case, the hypothesis would be: Flaky router will allow some (wired) clients to open web pages and not other (wireless) clients.  NB: The "connection" or "connections" to the "internal switch" is done in software....
agriboy1980Author Commented:
I will wait for the next wireless breakdown and try out some suggestions.
Will post the results.
agriboy1980Author Commented:
I have some update for you!
I had another wireless breakdown with couple of notebook users. There is one Lenovo notebook which is always the first to loose the connection. I have opened up  network and sharing center and checked the internet status. The router was not pingable. All I have done was pushed the "available wireless network" option, and disconnect the notebook's Wifi card  manually with the disconnect button and after connect it back to the same router.
Here is a thing:  After this notebook connected back to the same Router it received back the internet again, but the funny thing is that parallel at the same time the other notebook's Wifi card was working again (without having done anything)
How come? What should I do to avoid the next breakdown?

it seems possible that you experience interference. have you tried switching to a different channel ? if not, you should give it a try. normally it won't make a difference to your clients setup. pick one at least 2 channels away from the currently used one

if the above does not help,
- it might be worth a shot to try and see what information the router can display at that time. maybe it has logs or possibly a list of connected hosts together with their statuses.
- i'd also like to know the status of the wireless connection in windows at that time and the output if ipconfig /all
- does the problem always occur after a certain duration ? or a multiple of a certain duration ?
Fred MarshallPrincipalCommented:
From what you've told us, it's not clear to me if the problem is universal across all the wireless clients or just some of them / some of the time.

If it's all of them at once then I'd be back to the flaky router idea.

If it's only some of them at a time then perhaps the idea of interference is more likely.  You did change routers.  This means likely different power levels, different antenna patters, etc. all of which affect interference potential.  How big a difference was the change?  e.g. 802.11g to 802.11n?  Power?  Antenna type and location?

I would install a program like insider or NetStumbler on one of the wireless client machines and see what kind of signals are present with any strength.  Then I would choose a channel that has the least overlap and competing signals.

I have had bad results using a wireless router's automatic channel selection.  This *did* cause dropouts.  So that feature, if it's available, should be turned off in favor of a manually SET channel number.
agriboy1980Author Commented:
Thanks guys. I am going to do the above mentioned options and post the results here.
agriboy1980Author Commented:
As far as now it seems to be interference for me. I have changed the channel and waiting for the next breakdown.
Fred MarshallPrincipalCommented:
I highly recommend you use inSSIDer to visualize the channel overlap.  It seems to have the best display for this purpose.
agriboy1980Author Commented:
Will do it and post here the results.
honestly, i would not bother but if you can setup some kind of recording mode, you will be more likely to pick the culprit. it can be a nearby wifi but also punctual signals such as radio-triggered public lightings or a microwave oven.
Fred MarshallPrincipalCommented:
"Some kind of recording mode" suggests at least the ability to look at the signal to noise ratio.  It's a great idea but skullnobrains wouldn't bother either.  This is kind of hard to do because most of the software relies on the wifi hardware to report SNR.  You might need a hardware spectrum analyzer made for this purpose and those are a bit spendy.  Better perhaps to hire someone who has the capability.

The inSSIDer software that I recommended isn't any better in that regard.  It simply plots the *assumed* spectra for all of the wifi sources present according to their signal levels.  So, if you see that the spectra overlap and that your signal is not 30dB above the others then you should assume degradation.  This gets a bit "iffy" on the edges of the spectra where your signal goes to zero of course.   It's not going to be 30dB above some other signal and be zero at the same time!!  But, it's sure good for channel selection by itself.

Impulsive noise from a variety of sources may cause unexpected interference because it can be high energy and broad band (thus getting into your useful spectrum).  Other non-impulsive sources that are in your useful spectrum like microwave ovens and portable telephones can be sources of "noise" / interference.  These are going to be harder to determine but you get a long way by simply understanding this.

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