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Network been wonky for a week.

SiskaSiska ShortyRegistered User regular
edited November 5 in Help / Advice Forum
Our home network has been acting up for about a week. It not longer seems to be able to hand out IPs in an orderly, timely and steady fashion. It seems to be affecting ALL connected devices, BOTH wired and wireless. We don't all get disconnected at the same time. It's all random when it happens for anyone.

Our setup is modem --> router --> switch. We have tied unplugging them all for several minutes but no improvement.

The problem just started all of a sudden, no one has changed any internet setting on anything that they are aware. We have checked individual machines to make sure nothing was switched to a static IP, for some reason. But unless we missed one they are ALL dynamic.

This is what it's like for my computer (but it's pretty much the same for all of them) that's connected via an ethernet cable. When I start up from being off it will spend a couple of minutes connecting and disconnecting from the network. Then it will stay mostly on, but randomly getting kicked off now and then for a minute or so. The internet connection icon on my task bar will say "unidentified network" when it's not working.

I tried doing ipconfig /release and ipconfig /renew from the command prompt and it actually said the IP was already in use. So what can we do to figure out what is causing it and hopefully fix it? Is there some way we can check and see what is hooked up to the network, if there is some static IP mucking things up? Or if there is some DHCP server conflict? Could it be our ISP causing it and it's not an internal network problem, at all? We have not yet called our ISP since we own our own modem, so we don't expect them to be helpful.

Googling for answers has mostly given results on how to figure out why one individual computer can not connect to wifi which is SO NOT OUR PROBLEM!

Siska on

Posts

  • NEO|PhyteNEO|Phyte They follow the stars, bound together. Strands in a braid till the end.Registered User regular
    I am not an expert at networking stuff, but a few things that come to mind, in no particular order:

    1) Does your DHCP setup have a large enough pool of IPs to cover all the devices?
    2) Does your DHCP setup have an option somewhere that has it reserve IPs for devices? We had this one come up on us before, stuff wasn't getting assigned an IP and it turned out there was a setting that made it hold IPs for specific devices, meaning that there was a lot of IPs unavailable because they were being held for old devices we didn't even have anymore.

    It was that somehow, from within the derelict-horror, they had learned a way to see inside an ugly, broken thing... And take away its pain.
    Warframe/Steam: NFyt
    Zilla360
  • Inquisitor77Inquisitor77 2 x Penny Arcade Fight Club Champion A fixed point in space and timeRegistered User regular
    The first thing I'd do is a factory reset on the modem & router, followed by firmware updates.

    BahamutZEROPailryder
  • MugsleyMugsley Registered User regular
    Try moving your PC to a different Ethernet port. I wonder if the switch is starting to die. Similar for the wifi.

    Also have you had new neighbors recently? They could have set up a wifi router that causes channel congestion. You could try using a wifi scanning app to check channel congestion around you.

  • SiskaSiska Shorty Registered User regular
    I have tried switching to different ethernet ports on both the router and the switch for two computers. Both still continued having issues at least half the time on start up (and getting kicked sometimes, rarely). We have yet to try doing a factory reset. Everyone needs internet like they need oxygen in this house, so they are not quite there yet to give that a go. Since when we bought the modem 3ish years ago we had to spend over an hour on the phone with our ISP to activate it, or something, and are worried that will happen again. So that is hindering my troubleshooting a bit. But unless this miraculously fixes itself I'm thinking it may happen eventually. For now I just wish there was an easy way for me to see what the problem is (some static IP, DHCP messups...) without turning off everyones oxygen internet

    For now I have just told MY computer to not shut off its internet connection when going into power saving mode. So as long as I don't turn my computer off I am mostly fine. 8-)

  • RiboflavinRiboflavin Registered User regular
    "I tried doing ipconfig /release and ipconfig /renew from the command prompt and it actually said the IP was already in use."

    It sounds like an IP conflict. I'd shut off all but one computer, load some network mapping software and make sure I wasn't missing a device like a printer or something I might have forgotten about. Bring up the network one machine at a time. When the problem hits note the IP of the device having the issue, shut it down, check and see if you can ping the IP to see if there is a duplicate and double check on the map.

    Since it is intermittent is it possible someone is bringing a device from home?

    I don't think its the ISP unless for some wacky reason everyone has a public address.

    Also, I quit doing IT in 2007 so take it for what its worth.

    Feral
  • HydropoloHydropolo Registered User regular
    How many devices are on your network and how wide is your pool. Count ALL PCs, phones, tablets, media devices, IOT devices. I would hope you have a /24 pool and don't need more than 254 devices. That being said, I wouldn't be surprised if your setup is only slated to do like 50 addresses and so on. Depending on the number of people in your house, that's not even terribly difficult these days.

    If your subnet on your IP address is a /24 and the pool isn't the full /24, give one of your problem devices a static IP outside the pool and see what happens.

    Feral
  • mRahmanimRahmani DetroitRegistered User regular
    Losing IP addresses sounds like a router problem to me. Modem wouldn’t affect that and neither would switches (I think).

    Do you know anybody who could loan you an old router for a few days? Would be a good way to determine if something inside decided to go haywire.

    ShadowfireFeral
  • FeralFeral MEMETICHARIZARD interior crocodile alligator ⇔ ǝɹʇɐǝɥʇ ǝᴉʌoɯ ʇǝloɹʌǝɥɔ ɐ ǝʌᴉɹp ᴉRegistered User regular
    edited December 2
    Siska wrote: »
    I have tried switching to different ethernet ports on both the router and the switch for two computers. Both still continued having issues at least half the time on start up (and getting kicked sometimes, rarely). We have yet to try doing a factory reset. Everyone needs internet like they need oxygen in this house, so they are not quite there yet to give that a go. Since when we bought the modem 3ish years ago we had to spend over an hour on the phone with our ISP to activate it, or something, and are worried that will happen again. So that is hindering my troubleshooting a bit. But unless this miraculously fixes itself I'm thinking it may happen eventually. For now I just wish there was an easy way for me to see what the problem is (some static IP, DHCP messups...) without turning off everyones oxygen internet

    For now I have just told MY computer to not shut off its internet connection when going into power saving mode. So as long as I don't turn my computer off I am mostly fine. 8-)

    The replies from mRahmani, Hydropolo, and Riboflavin are good.

    I want to focus on the sentence "For now I just wish there was an easy way for me to see what the problem is (some static IP, DHCP messups...) without turning off everyones oxygen internet" because that means thinking about this as a system administrator would for a corporate network where you can't take everything down all at once.

    Here is what I would do in this situation:
    1) Log into your router and try to get a list of current DHCP leases. This should show you the IP addresses that your router has issued to various devices.
    2) Obtain the DHCP pool settings, particularly the DHCP range that your router will issue. This will be something along the lines of 192.168.1.50 - 192.168.1.200. Confirm that the range is big enough for your house.
    3) Download some network mapping software like Riboflavin said. My suggestion is Zenmap. This is the GUI-enabled version of nmap for Windows. It's not the easiest software in the world to use, but it's powerful, and it's a common standard so there are plenty of guides and help for it online.
    4) Use that network mapping software to scan your entire subnet for devices. You probably have a network like 192.168.1.0 - 255 (aka 192.168.1.0/24), so scan the entire range.
    5) Go around to any devices you can access or any of your housemates who are willing to cooperate, and get them to give you the IP address and MAC address of that device. For example, ask each of your housemates (if they are using Windows) to do ipconfig /all and print out or email you the results.

    Once you have all that information, what are you looking for?

    First off, you're looking for evidence that your DHCP pool has been exhausted.

    Example: if your DHCP pool is only 192.168.1.50 - 192.168.1.100, and all of those addresses show up in the list of DHCP leases, then you're just out of addresses. Expand your DHCP pool. (Also consider adjusting the DHCP lease duration. I like to use 8 days for private networks.)

    Second, you're looking for any sort of mismatch between the results of the network scan vs the output from your router.

    For example, if Zenmap tells you that there's a device on IP address 192.168.1.55, but your router does not report 192.168.1.55 as a valid DHCP lease, then either (a) there's a device on your network statically configured with that IP or (b) there's a rogue DHCP server running on your network.

    Another example: if Zenmap tells you that the device on 192.168.1.133 has MAC address 00:11:22:AA:BB:CC, but your router says it has given that IP address to a device with MAC address 69:B0:0B:13:54:20, then either (a) there's a device on your network statically configured with that IP or (b) there's a rogue DHCP server running on your network.

    Finally, you're looking for concordance between the outputs of your network scan, your router, and the IPs/MACs given to you by your housemates.

    Every computer should report the same DHCP server IP address. That DHCP server IP address should be the same as the IP address of your router.

    Every computer should report a MAC address and IP address that matches up with both your network scan and the DHCP lease list from your router.

    Once you've got all that information in hand and you're sorting through it, you may observe some anomaly that I haven't identified. You seem to have a good grasp of the concepts here, so I feel pretty confident in your ability to find an unusual needle in this Ethernet haystack. But if there's some concept here you want clarification on, feel free to batsignal me and ask.


    Feral on
    MechMantis
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