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Old 10-22-2013, 05:25 PM   #1
mfan
LQ Newbie
 
Registered: Sep 2010
Location: Germany
Distribution: Ubuntu 11.10, 12.04
Posts: 18

Rep: Reputation: 0
Connected to wireless, no internet, cannot ping router


Hi there!

I am having trouble with a wireless network. I get connected, but I have no internet access.

Sometimes it works, sometimes not. When not, I cannot ping the router (192.168.178.1). I even tried to connect with a cable and sometimes (but NOT always) couldn't ping the router. Nevertheless, accessing the router interface from my android mobile, I could see my computer among the connected devices.

The router is a Fritz!Box. My flatmates can connect normally (but they don't have linux q-. I can also connect perfectly from my mobile phone.

Because we have had another issue, low signal at the other end of the apartment, we also bought a Fritz!Box wlan repeater. At the moment, I am connected to it with a cable, and I do have internet access.


Code:
~ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         fritz.box       0.0.0.0         UG    0      0        0 eth0
link-local      *               255.255.0.0     U     1000   0        0 wlan0
192.168.178.0   *               255.255.255.0   U     1      0        0 eth0
192.168.178.0   *               255.255.255.0   U     2      0        0 wlan0
Code:
~ arp -a
fritz.box (192.168.178.1) at 24:65:11:57:75:36 [ether] on eth0
fritz.box (192.168.178.1) at 24:65:11:57:75:36 [ether] on wlan0
Code:
~ ping 192.168.178.1
PING 192.168.178.1 (192.168.178.1) 56(84) bytes of data.
64 bytes from 192.168.178.1: icmp_req=1 ttl=64 time=1.80 ms
64 bytes from 192.168.178.1: icmp_req=2 ttl=64 time=2.24 ms
...
If I disconnect the cable, I am still connected through wireless, but I have _no_ internet access


Code:
~ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         fritz.box       0.0.0.0         UG    0      0        0 wlan0
link-local      *               255.255.0.0     U     1000   0        0 wlan0
192.168.178.0   *               255.255.255.0   U     2      0        0 wlan0
Code:
~ arp -a
? (192.168.178.1) at 24:65:11:57:75:36 [ether] on wlan0
? (192.168.178.53) at 08:96:d7:08:61:04 [ether] PERM on wlan0
Code:
~ ping 192.168.178.1
PING 192.168.178.1 (192.168.178.1) 56(84) bytes of data.
^C
--- 192.168.178.1 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 14043ms
Any suggestions?

Thank you in advance!
 
Old 10-23-2013, 03:51 AM   #2
cospengle
Member
 
Registered: Feb 2008
Location: Armidale, NSW, Australia
Distribution: Fedora 8
Posts: 32

Rep: Reputation: 6
I always cringe when someone suggests this as a solution, but have you tried rebooting the wireless AP?

Even if that doesn't solve you problem permanently, if it works after rebooting then it might point to some caching issue.

BTW, when you say "I could see my computer among the connected devices." that does not always mean "connected". Some home routers will cache devices that have been previously connected and display then as being connected (I know mine does). There might be an option to delete that entry on the router interface - if you do that and try to connect wirelessly, do you still show as connected?
 
Old 10-23-2013, 03:32 PM   #3
nini09
Senior Member
 
Registered: Apr 2009
Posts: 1,893

Rep: Reputation: 163Reputation: 163
It look like signal is too weak. To confirm it, you use command iwconfig wlan0 to check link quality with repeater and without repeater.
If signal strength issue, try to change channel number or use low speed.
 
Old 10-24-2013, 01:00 PM   #4
mfan
LQ Newbie
 
Registered: Sep 2010
Location: Germany
Distribution: Ubuntu 11.10, 12.04
Posts: 18

Original Poster
Rep: Reputation: 0
Of course I rebooted the router. It didn't helped. I checked the listed devices in the router web interface and tried to delete my laptop. It didn't help as well. The channel settings are at "auto". Next time I can't connect, I will try the manual. There is a small chance that this is the issue.


Let me mention a few more details. At our shared apartment we have a Fritz!Box router (let's call it "original"). My room is at the other side of the 75m2 flat of an "altbau" with probably thick walls, and there the signal is not too good. BUT my android phone can connect to the original-router and surf at the net, possibly at somehow low speed. At the same time, my Ubuntu 12.04 Lenovo T420 laptop couldn't connect at all to the router. I tried to go very close, still nothing. I plugged a cable and still (!) I couldn't connect.

Then, I tried various things from my laptop in an attempt to figure out what was wrong. As I was querying the arp cache with arp -a, (which actually does NOT modify anything, right?), I saw that I could now connect to the internet and ping the router, enter its web interface, etc. Couldn't explain, but it worked. Then I went back to my room and I could use the internet.

But some time later in the same day, I couldn't connect any more. I tried querying again with arp -a. Nothing. I rebooted to windows just curious, and I saw that windows could connect to the internet. Seems there is some issue with the arp cache (or something else) in my linux box.

A few days later, I bought a repeater (Fritz!Box Repeater 300E) connected it at my room and tried my luck. No big surprises. The repeater connects to the original router automatically and reproduces the signal. The signal in my room now was quite strong, but sometimes I could connect by wireless at the repeater, sometimes not. When I couldn't connect by wireless, I used a cable. That worked.

So actually I do have a workaround now. But I do like to figure out what happened and why. Plus, the repeater costs €69 which would be nice to get back by returning it if I don't really need it.

Thanks for your time!
 
Old 10-24-2013, 04:46 PM   #5
nini09
Senior Member
 
Registered: Apr 2009
Posts: 1,893

Rep: Reputation: 163Reputation: 163
Now it look like Linux box has problem or Linux kernel isn't stable. In general for the kind of issue, syslog should be checked. If lucky, some warning or error is in syslog. They can give you a clue.
My suggestion is that you can change Linux distribution, such as Fedora, OpenSuse and so on. Other distribution could help the issue.
 
  


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