Since about a week, every second day or so, my Internet connection gets stalled on my laptop for no apparent reason.

I am on a shared Internet connection and got an Ethernet cable from my landlord. I got three computers, normally all of them up and running when my laptop is on.

My laptop has a static IP address as well as the other two computers, a PC and an SBC.

When the browser on my laptop gets stalled, I check the connection and ping doesn't work. But ping works on the PC and on the SBC on the same network.

With the graphical Network Manager within xfce, I disconnect the Ethernet connection and connect it again, immediately.

And then it works again about one or two or three days until it happens again. Does someone has a clue what could be the reason for that or where to search for?

Have you examined your log files for evidence?
Did you ping by IP address or name for that test, and what did you ping?
Did you check your reported network settings and routing both before and during one of these events?
What is the make and model of laptop? Can you report the NIC used for network access?
What is installed on this laptop? Both distribution and version may be of some use.

You might want to review the site suggestions for submitting questions here. They may help you provide enough information to make better sense of your question and properly enable a reasonable answer or two.

This problem and hence the question may have a simple reason but it's not a typical question. I can deliver a bunch of details but the first question would still be WHERE to search for.

Those log files e.g. are both older than the problem itself:

An important question is still why does this happen only in the very last week? There have been no changes of hardware or fundamental changes of software.

One reason could be that there is a config file that is permanently used and such a file gets corrupted for some reason. If I take out the connection in the Network Manager and put in the same connection again, such a config file would be newly set up again. Only one possible scenario.

When I ping, I ping "google.com". I ping always the same on the three computers. When it works on two of them, it should work for the third one, too. All of those computers have a standard setup for networking. Nothing is altered by me in regards to firewalls or routing tables or something similar.

The question remains: why does it happen suddenly and at a first look "randomly".

The next info also just for completeness.

How is every thing connected together and to the landlords cable?

Are your computers behind your own router?

Have you tried swapping out the ethernet cable for a known good cable?

I once had a connection issue that, with the help of an excellent support tech from my ISP, was tracked down to a dodgy cable.

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The landlord owns the router and gives me an Ethernet cable. That goes into a switch on my desk with five ports. One is for my own WiFi access point where I connect my phone to. The other three ports go directly to my laptop, PC and SBC.

But I'll follow the hint from user frankbell and try another cable.

Perhaps just switch cables and see if the problem moves to another device. If it moves, it's probably the cable. If it stays, it's the computer. It might take awhile for the problem to manifest itself, of course, since it's intermittent. If it doesn't come back at all, profit.

If you are using static IP addresses have you verified they are outside the range of the DHCP server?
Your symptoms at first glance look like duplicate IP addresses.

Exaxtly, I don't know if my landlord is using the usual range but from time to time I do a "sudo nmap -sn ..." and I have never seen any addresses from other devices higher than 150. The majority of those floating addresses is under 70.

There is only a TP-Link router at address xxx.254, and my WiFi access point is at xxx.253. The laptop has xxx.200, the PC xxx.201, and the SBC xxx.202.

I would like to see the output of that ping request. Doies it at least resolve google.com to an IP address for the ping.

The logs of interest would NOT be under /var/log/arp, rather files directly under /var/log. The file /var/log/messages might pertain.

I will be interested to see what results result from the jumper swap. That would be a cheap fix. Luck!

Have you tried changing the address? Most DHCP servers assign random addresses within the range.

How are you insuring that your computers get fixed IPs without access to the landlord's router?

I was going to suggest blaming it on Comcast but I see you're not in the U.S. :^D

Q: Are the other computer affected with the stalling at the times your laptop is?

I would try, on all three computers, pinging the same external site and see what the transit times are. (I would normally use `clusterssh' -- try: `man cssh' for more and you'll need SSH keys configured on your systems -- to do a test like this w/o having to login into each system and issue the commands separately. But... it's fine if you don't have that utility installed.) If the transit times are long on all three systems, the problem is external. Having to rely on network equipment that you don't have any control over makes fixing this more complicated. It's rather like trying to fix slow network access at a coffee shop.

If, however, the transit times are long on only a subset of your systems, concentrate your log file inspections on those systems.

Q: Are you experiencing these pauses while browsing any/all web sites or only certain ones?

Q: On the laptop where you see this most frequently... how much RAM does it have? Can you tell if it's swapping madly during the times when your network connection seems slow? Some web page creators seem to believe that they are the only page you should be viewing and their page(s) will consume a lot of RAM. Run vmstat(1) for a while
(5s interval, 500 times---choose whatever values you like) for a while and watch the memory and swap activity while you're working on the laptop. If you see swapping is occurring (the `si' and `so' columns will show `0' if there's none) you're low on memory---the pauses you're seeing are probably the system shuffling programs in and out of swap space. No swap space you say? You will likely need to create some.

If you're a multi-tab web browser (like me) you can easily run out of memory. One solution that has helped me cope with my multiple tab habit is a plug-in like `Tab Suspender'. Idle tabs are saved off to disk after they haven't been actively viewed for a few minutes and only a placeholder remains in memory until you re-select the tab.

Hope this helps a bit...

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Surely, but I said already that I am pinging the same command on all three computers and Internet always works with the two others.

Until now, I presume that could have been the cause. Important was the info from frankbell (post #5) because I wouldn't believe that a software action in Network Manager, i.e. disconnecting and re-connecting, fixes an hardware issue.

As I stated in post #9, all the DHCP addresses are always below xxx.150, most of them below xxx.70. None of them ever seen in the range above xxx.149.