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Consider the following setup: 2-3 Laptops and 4-5 Desktop PCs (both windows and linux systems) are connected to an ADSL modem/router (http://avm.de/produkte/fritzbox/fritzbox-3272/) via wireless and LAN. The LAN network consists of 2-3 switches of questionable quality as well as lan cables in awful conditions.
Now everything worked fine until someday the internet connections stopped working with limited connectivity errors in windows. I did some of the usual router on/off cable in/out tests and everything worked fine again. Next day I got a call again, internet not working. This repeats for like 5 times and right now I figured the following pattern: If I plug a device directly (no switch inbetween, no wifi) in the router lan port, connections work instantly and fine. If I unplug the device then, wifi and LAN via switches works directly after. But then, after some time, limited connectivity again. This is so hard to fix since I get everything to work, leave, and the problems occur sometime after that.
My main question is, is this certainly a router problem, or is it possible that some device in the network (broken cable/switch, infected pc or whatnot) causes routing issues for the entire network?
sweetguest
Posted 2014-09-17T08:04:07.150
Reputation: 21
What IP addresses does the windows PC have, when it reports connection errors? Can you ping the fritzbox? Does Name resolution work? Is there a rouge dhcp server? – Jonathan – 2014-09-17T08:47:21.747
Are they connecting both Wifi and LAN at the same time through the same network? Also, what device does DHCP and are there enough free slots to give out IP addresses? It sounds like either the DHCP lease is not being renewed and/or an ip conflict. – LPChip – 2014-09-17T10:48:53.040
@Jonathan I'll report back as soon as another error will occur – sweetguest – 2014-09-17T11:30:53.470
@LPChip No single device is connect with both wifi and LAN, but the Router is managing both (and also responsible for DHCP) I can also see the connected devices on the router frontend with no obvious ip issues (all ips are unique) – sweetguest – 2014-09-17T11:34:45.067
@sweetguest do you have enough free DHCP slots available though? – LPChip – 2014-09-17T12:57:29.200
@LPChip haven't read whole thing but what on earth is a free DHCP slot? typically a DHCP IP range is very large. like maybe 192.168.1.2-254 – barlop – 2014-09-17T17:31:38.110
If I were you I would troubleshoot.. Try different hardware – barlop – 2014-09-17T17:32:54.233
@barlop the default settings for DHCP can be anything. I've seen 50-100, 50-199, 100-199, 2-254, etc. If it is 50-100 or sweetguest has changed the range himself, and its full now for whatever reason, problems can arise. Might not be the case here, but its better to double check than to search for something else, later to find out, this was the problem. – LPChip – 2014-09-17T17:41:10.223
@LChip I don
t know the DHCP range, but I will check next time I am on site. Im confident that thats not the problem though, since I can see the connected devices on the router frontend. The devices with limited connectivity have an ip address, the icon even indicates that they`re connected to the router, but not to the internet for whatever reason. – sweetguest – 2014-09-17T17:46:04.443@barlop thats why I`m asking. Is it possible that a single broken part of the network (cable, switch,computer, malware etc) can cause connectivity issues for the whole network? Because I thought thats not possible, so the error must lie within the router. – sweetguest – 2014-09-17T17:49:20.093
@sweetguest I haven't read the whole thing but a hardware fault on a router could affect the whole network. And I think when an issue is sporadic and quirky and not something that is likely to be something somebody programmed, then it points towards hardware. There may be a setting that it's related to, but still swapping parts e.g. swapping the router can help isolate if it's that. – barlop – 2014-09-17T18:06:44.643