SOLVED: Cannot Ping Device From Some Computers On Network

If 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
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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
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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