Windows 10: Windows 10: Unable to Ping and missing arp table entry mystery

I am debugging a network issue on my home LAN that is driving me crazy. LAN setup is pretty typical:

• 1 router Asus RT-AC5300
• Desktop with wired connection to router.
• laptop1 with wireless connection to router.
• laptop2 with wireless connection to router.
• raspberrypi4 with wireless connection to router.

The problem is I cannot consistently ping the raspberry pi. If I login to the router I can see in the client list and ping the raspberry pi, and generally not always I can successfully ping it from the desktop with a wired connection.


Troubleshooting steps taken so far with no success.

• Disable IPV6 on all computers.
• Update router firmware and reboot what feels like 100 times.
• disable firewalls on all computers.
• disable wlan power saving on pi.
• manually add gateway 192.168.1.1 info to the laptops
• run a combination of: netsh winsock reset, netsh int ip reset, ipconfig /release, ipconfig /renew, ipconfig /flushdns

What I have noticed and makes sense is that when I issue arp -a on any windows machine and if it is missing the entry for the raspberry pi I get a "Destination Host Unreachable" error. Makes sense. I guess the million dollar question is why do some of my windows machines have an entry for the raspberry pi and some do not? To be clear I am using the raspberry pi as an example but I've seen a similar issue just with other windows laptops on the network as well so don't believe it is a raspberry pi issue.


One more observation: when my desktop can successfully ping the raspberry pi and the laptops cannot I ssh into the pi and if I ping either of the laptops from the pi to the laptop as the pi has the right entries in the arp table, it is successful and after I do that the proper arp entry shows up now in the windows arp table arp -a and I can successfully ping the raspberry pi from laptop1 or laptop2.


Ok, one more observation: after it is working as above, if I close the laptop screen and put it to sleep when I open it back up and re-run the "arp -a" the table is much shorter and missing the previous raspberry pi entry and I can no longer ping it!


If you've read this far, thank you. Is summary my question is why do my laptops seem to be missing the arp entries that they need to ping other devices on the network? I tried adding the arp entry manually as admin on the windows laptops with "arp -s ip_addr mac_addr" but it never shows up in the table .


Thanks for any troubleshooting tips you can offer...I'm at the end of my rope and ready to buy a new router but flashing new firmware didn't change anything so I am skeptical a new router will help.


Greatly appreciated

:)

 

ARP Entry Information

In general, address resolution is handled by the IP stack and not something one modifies. Why do you want access to the ARP table?

Open a command prompt window as administrator and enter arp -a to display the ARP cache.

 

Window 10 arp cache

Windows desktop pcs not showing my gateway router ip in arp table. Hence not able to browse pages of servers connected beyond my gateway router. Gave netsh interface ipv4 add neighbors....with store=persistent. A static entry comes and browsing is fine.
But next day entry disappears and have to do daily. Dynamic updation is sometimes okay but goes often. This problem is not seen for a handful of xp pcs. Any solution for permenant static entry in arp table for windows 10

 

ARP Entry Information

Where can I get ARP Entry information? Are they stored in a file?