Windows 10: Can ping ipv6 but not ipv4 on LAN

I just moved into my business partner's home office and I am trying to get Dev (computer #1, Win10 Pro) to see DbServer's (computer #2, also Win10 Pro) Postgres Database to no avail so far.

He has a Comacast router which seems to be using using IPv6 primarily. When I go to WhatisMyIP, I get a v6 address. Ok, I think finally time to get my head around IPv6.

During debugging I ran an interesting effect which may or may not be the related to my connectivity problems.

Dev can ping DbServer's v6 address but not its v4. DbServer can ping Dev's v4 address but not its v6. *Eek I can RDP into DbServer from Dev using either v6 or v4 just fine.

:)

 

Win 10 IPV4 name resolution intermittently dropping

I have a Win 10 box on my office network that will intermittently lose its ability to resolve IPV4 names.
When the issue occurs the user can not get to any external internet website.
I have narrowed the issue down to some type of networking issue on the Win 10 box, but can not figure out what it might be, or what my next diagnostic steps should be.
Here is what diagnosis I have tried.



1. Ruled out ISP issue, as all other computers in our small office have internet connection when this issue occurs on this box.



2. Ruled out internal LAN DNS issue, as all boxes receive their DNS and DHCP configuration via dnsmasq.
Checked and compared this box with others in the office and there is no significant difference.



3. Compared routing table and arp cache with other working boxes and found no significant difference between them.



Symptoms when the issue is present:



a. Ping external web site by name. *Does not work.*

C:\WINDOWS\system32>ping meridianenv.com

Ping request could not find host meridianenv.com. Please check the name and try again.



This site is known to be up and responding at the time of this check.



b. Ping external web site by IPV4 address. *Works.*

C:\WINDOWS\system32>ping 66.160.145.21

Pinging 66.160.145.21 with 32 bytes of data:

Reply from 66.160.145.21: bytes=32 time=26ms TTL=54



Ran this test immediately back to back with the previous test. Then immediately reran the previous test and the result was the same as above.



c. Ping to another internal LAN box by name. *Works*, but responds with IPV6 instead of IPV4.

C:\WINDOWS\system32>ping jab-prec3610

Pinging jab-prec3610 [fe80::28f1:3c0b:c6a8:91ea%3] with 32 bytes of data:

Reply from fe80::28f1:3c0b:c6a8:91ea%3: time<1ms



d. Ping to another internal LAN box by IPV4 number.
*Works.* This is the same box as immediately above.

C:\WINDOWS\system32>ping 192.168.112.101

Pinging 192.168.112.101 with 32 bytes of data:

Reply from 192.168.112.101: bytes=32 time<1ms TTL=128



e. Ping from another internal LAN box, back to the problem box, by name.
*Works.*

C:\Users\jeffb>ping acct-opti5040

Pinging acct-opti5040.mei.lan [192.168.112.108] with 32 bytes of data:

Reply from 192.168.112.108: bytes=32 time<1ms TTL=128



f. Ping from another internal LAN box, back to the problem box, by IPV4 address.
*Works.*

C:\Users\jeffb>ping 192.168.112.108

Pinging 192.168.112.108 with 32 bytes of data:

Reply from 192.168.112.108: bytes=32 time<1ms TTL=128



When the box is working properly I reran these same tests, and the following two results changed (items *a* and *c* above).



a. Ping external web site by name. *Works.*

C:\WINDOWS\system32>ping meridianenv.com

Pinging meridianenv.com [66.160.145.21] with 32 bytes of data:

Reply from 66.160.145.21: bytes=32 time=33ms TTL=54



c. Ping to another internal LAN box by name. *Works* and returns with IPV4 info.

C:\WINDOWS\system32>ping jab-prec3610

Pinging jab-prec3610.mei.lan [192.168.112.101] with 32 bytes of data:

Reply from 192.168.112.101: bytes=32 time<1ms TTL=128



Other things I have tried:



1. Flush the Windows DNS cache. Did not fix the issue.

C:\WINDOWS\system32>ipconfig /flushdns

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.



2. Reset the IPV4 interface.

C:\WINDOWS\system32>netsh int ipv4 reset reset.log

Resetting Interface, OK!

Resetting Unicast Address, OK!

Resetting Neighbor, OK!

Resetting Path, OK!

Resetting , failed.

Access is denied.

Restart the computer to complete this action.



Not sure if this is successful, as it says resetting failed and access is denied.
Then it states that it requires a reboot to take effect.
While resetting the interface and rebooting the system may temporarily resolve the issue it is impossible to tell if the resolution is a result of the reset or the reboot.
Since the system has been rebooted each day, this does not appear to be a solution to the issue.



3. Reset the IPV6 interface.

C:\WINDOWS\system32>netsh int ipv6 reset reset.log

Resetting Interface, OK!

Resetting Neighbor, OK!

Resetting Path, OK!

Resetting , failed.

Access is denied.

Resetting , OK!

Resetting , OK!

Restart the computer to complete this action.



Same conclusion as with resetting the IPV4 interface above. This does not appear to be a solution to the issue.



This issue does not occur with any of the other Windows boxes in the office (mostly Win 7, and one other Win10 box).
When the issue happens, it may only occur for a minute or two, or may last for 10 plus minutes.
I can not correlate when it happens, or when it fixes itself, to anything else happening on our network.



I am looking for additional suggestions as to what might be causing this issue, diagnostic options, or what might fix it.



Thanks for any assistance.

 

Checking media [Fail]

Hi Kalpana,

Thanks for trying to assist me. I have gone through the link you suggested, some people having similar problems got theirs fixed by changing the boot sequence as follows:

UEFI BOOT:

Windows Boot Manager

UEFI Onboard LAN IPv4

UEFI Onboard LAN IPv6

Unfortunately, I only have this two options:

UEFI BOOT:

UEFI Onboard LAN IPv6

UEFI Onboard LAN IPv6

Any other suggestions will be welcomed, thanks in advance.

 

It's rare for most routers to use ipv6 on the LAN disable it on all PCs make sure all PCs are in the same workgroup and all have ipv4 IP in the same range make sure NetBIOS is running on all PCs

 

While looking around for the settings you want I noticed that DbServer was on a Public Network while Dev was correctly on a Private Network. The last time I moved this computer it defaulted to Public network then as well.

My database access is working now. though interestingly, neither computer can now ping the others IPv6 address, just the v4 addresses.



The IPv6/v4 ping pro