SOLVED: Cannot Ping Device From Some Computers On Network

ping-2If you have a device (webcam, printer, PC, server…) that you can connect from from most computers on your network but not others, there are two common reasons for you to investigate:

  1. The device has a firewall or antivirus product that is actively blocking the traffic
  2. The device has a misconfigured network, specifically the Subnet Mask

In my case, I was working on a security appliance that was using a statically assigned 255.255.255.0 for the subnet mask when it should have been 1 class C larger 255.255.254.0.  This meant that all of the PC’s with an IP in the lowest range (10.10.10.1-255) could connect fine but PC’s in the second range (10.10.11.1-255) could not.  It was a simple fix to correct the subnet mask but it took me 2 frustrating hours to figure out so I thought my pain might be your gain.

TROUBLESHOOTING NETWORK CONNECTION PROBLEMS TOP 10:

  1. Try to ping the IP address (not the name) of both the PC and the device you cannot connect to, from themselves
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  2. Try to ping the IP address (not the name) of both the PC and the device you cannot connect to, from a different PC, preferably in a different location (different floor, office…)
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  3. Turn off any firewalls, AV or Malware protection (yes, just for a minute so you can test)
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  4. Check the Subnet mask on both systems
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  5. In an elevated CMD prompt, try TRACERT <IPADDRESS> to see where the traffic stops
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  6. In an elevated CMD prompt, try NETSTAT -R to list off the routes and see if anything seems odd
    .
  7. If pinging the hostname is not working but the IP address is, you may have something misconfigured in your DNS or your HOSTS file so check your HOSTS file stored under C:\Windows\System32\drivers\etc
    .
  8. If the device you cannot connect to has a DHCP address, assign it a static IP, Subnet and DNS
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  9. Reboot both the PC and the device to clear any routing issues or crashed services
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  10. If all else fails, the problem may be in a network switch between the PC and the failing device so manually clearing the ARP table on that switch (or switches) or just rebooting that switch may help

 

Comments

  1. Avatar
    Nom De Guerre February 4, 2019 at 8:08 am

    I have one of these at the moment. Except it’s not a subnet mismatch/difference or device Firewall/ACL/Security settings (device has an admin password set, but no other security settings are enabled). I’m having trouble with an HP LaserJet Pro M201dw. I can ping it just fine from my Windows workstation and a MacBook, but not from a Windows print server or some other workstations. The print server had been able to send jobs to the printer until fairly recently, it started frequently appearing as offline. Yet I can set up a network connection and print with no trouble from a workstation that can ping the printer. The M201dw connects wirelessly to a UniFi AP HD. I’m not using UniFi Security Gateway, firewall rules. Pretty basic set up.
    I told the main user of the printer I should have the problem resolved by end of 2019. 😉

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