Internet connection randomly stops ?

[Grizzley]

Recently as in the past few weeks, my internet connection on a computer will just randomly stop. Upon restarting the computer, although usually twice the internet will work again; but only for a short while before it stops working. The internet icon in Windows11 displays the internet connection as working but not any browser ?

[icecream-guy]

can you provide a network diagram so we all know how this is all setup

is this wired or wireless network?  if wireless there may be contention from another radio nearby.
is this a PC or Laptop? If laptop is it possible that the NIC may be going to sleep.

is your modem possible loosing it IP and default gateway.

I'd suggest to also load up Wireshark and capture some packets to troubleshoot what is going on.

[deanwebb]

Also, what kind of Internet is this? Satellite? Borrowed from a neighbor? Cellular? Cable? Fiber?

[Grizzley]

can you provide a network diagram so we all know how this is all setup

is this wired or wireless network?  if wireless there may be contention from another radio nearby.
is this a PC or Laptop? If laptop is it possible that the NIC may be going to sleep.

is your modem possible loosing it IP and default gateway.

I'd suggest to also load up Wireshark and capture some packets to troubleshoot what is going on.

What method would you preview to provide a network diagram ?
This is a wired network. How should I save the information from wireshark, or simply just a screen capture ?
The internet connection is Fiber.

[icecream-guy]

you can draw something in your favorite drawing app, I like MS paint.
the wireshark captures would be for your own use.

[Grizzley]

Using WireShark it lists the same IP numerous times with the info.

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Destination unreachable (Host unreachable) with protocol ICMP ?

Therefore, it's finding out what is causing this IP which I'm familiar with, to fail ?

[icecream-guy]

what are you pinging?  it sounds like you are losing your default gateway, and cannot route,  are you pining the next hop IP or something else on the internet, try ping next hop IP if you are pinging something else.  you can also use traceroute to figure this out. traceroute to 8.8.8.8 or something like that.

[Grizzley]

what are you pinging?  it sounds like you are losing your default gateway, and cannot route,  are you pining the next hop IP or something else on the internet, try ping next hop IP if you are pinging something else.  you can also use traceroute to figure this out. traceroute to 8.8.8.8 or something like that.

The IP address which is returning destination unreachable is pingable. Trace Route is returning host unreachable. What exactly is causing this issue ?

[Dieselboy]

what are you pinging?  it sounds like you are losing your default gateway, and cannot route,  are you pining the next hop IP or something else on the internet, try ping next hop IP if you are pinging something else.  you can also use traceroute to figure this out. traceroute to 8.8.8.8 or something like that.

The IP address which is returning destination unreachable is pingable. Trace Route is returning host unreachable. What exactly is causing this issue ?

If you ping say, 7.7.7.7 and an IP (not 7.7.7.7) replies to say destination unreachable, this can be an indication that the device which is replying does not know how to route to the destination and your traffic has gone as far as at can go, and no further. For example, next hop is down or link down from that device which sends the "destination unreachable" message.
You will also get something like this at home if your local internet is down and your local modem/router has lost its upstream route (ie internet connection). But you will also get this reply from internet routers that are routing global internet traffic.

You shouldnt need to reboot your machine to fix internet issues. I think that the fact you sometimes need 2 reboots to resolve the issues suggests to me that the actual reboot is not doing anything positive for you except consuming time, long enough for the (intermittent) issue that you are seeing to go away. Though, reboot can clear cached entries for some things so can actually help when it is those cached entries being the issue (ARP table for example).


When I come across problems like you described in your first message I always default to a process which works for me. In summary, I would set up multiple simple ping tests in the first instance and leave them running until the issue is encountered. As soon as the issue starts, glance at all of the ping tests and note which ones are no longer receiving ping replies. It's key to have significant devices being "pinged" and very quickly be able to check on them during the issue to get insight.
Therefore it should be clear that the "significant devices" is the important factor here and here is the list that I recommend:

1. your local default gateway
2. your local default gateway's default gateway (this is the ISP upstream router in their network and is your routers gateway to the internet, ie your routers next hop - this IP may change over time)
3. A couple of different stable IP's on the public internet - 1.1.1.1 and 8.8.8.8 should be good enough, these are public DNS servers
4. Your assigned DNS server(s) if DNS is not pointing to your local gateway (point 1) else dont bother with this if the IP is the same as point 1.

How to find the IP's:
To find point 1, you will open cmd.exe on your computer and run "ipconfig /all". You will see "Default Gateway" listed there. If a lot of output is making it difficult, use this command to filter based on Default Gateway:

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ipconfig /all | find "Default Gateway". You can run a trace route instead to get this IP as a second option. Try "tracert -d 1.1.1.1" and a list of IP addresses will be returned. The first IP (ie the first hop) should be your default gateway which should also be your local modem/router. The 2nd IP listed should be the upstream ISP router.

For point 2: see the "tracert -d 1.1.1.1" output and the IP which you need is the one listed after your default gateway IP. A few assumptions being made here but I expect this IP is somewhere within your internet providers network. You need this IP because you need to later on see if the internet outage you keep having is because your actual internet connection (not wifi) is dropping out.

For point 4 (3 is already explained) you can look at "ipconfig /all" again and find DNS Servers.


How to run the simultaneous pings:

Now you have a list of IP addresses noted, open up a cmd.exe window for each IP address. Ie, 4 IP address needs 4 x cmd.exe.
In the first window, run "ping -t [gateway ip]". So if you have ip 192.168.1.1 for the gateway then run "ping -t 192.168.1.1" and press enter. This sets of the ping tests and continues pinging indefinitely each second or two. Position this somewhere on the screen that can be seen and not covered over by the other cmd.exe windows

Repeat the above for all of the IP addresses so that you have a set of windows running pings.

Now all you need to do is wait for the issue to occur again and then take a look at the windows and note which ones are showing "timeout" instead of "reply". Then you can match what you actually see to an expected experience below:

Expected experience:
This is where the network diagram comes in very handy. But let's assume you have a basic home network that the majority of people will have when they sign up to $ISP and the ISP sends them a modem to plug in without any guidance with regards to wifi design (physical location, location with regards to other radio sources, radio strength, radio channel, number of devices, antenna positioning etc).
Assuming you have a common simple network, the diagram would be like this:

Desktop computer -> plugged into router -> Internet (Cat6 copper ethernet cable connecting to FttP NTE (basically fibre run inside the home and a shoe-box side wall box to convert from fibre to ethernet cable))

If your internet connection is dropping, for example dodgy connection with the fibre or copper or it's xDSL and the signal sync is dropping and causing the modem to re-train (lights on the modem will indicate this in most cases with a flashing DSL light which will go solid (not flashing) when it has re-sync to the line and internet should be working shortly after) - if this is occurring then your ping windows will show:

1. gateway - consistent ping replies
2. ISP - time out
3. Internet IPs - time out

If it's the local connection between your computer and home router then you would expect to see:

1. gateway - time out
2. ISP - time out
3. Internet IPs - time out


You'll probably find that the IP being shown in those messages that you see "reply from x.x.x.x destination unreachable" is your local modem or was discovered with the trace.