NetGear DSL Modem router issue DGND3700v2 PC to PC communication issue on LAN

[spidy_web]

I'm having a strange issue that I really need help to solve. My router seems to be blocking communication between some devices (computers and printers) on my LAN. I see them in the router list of connected devices with the same IP address as what each device reports that it actually has. When I try to ping or otherwise talk from one computer to another or to a wireless printer the device isn't found. Even pinging the IP address from one computer to another fails with not found. I go and reboot the router and it works fine for a while (I also reboot the router once a week through a timer). In a couple of day the issue returns and I have to reboot the router again. Some times it works if I reboot one or both of the computers, but even then it almost always stops after a few minutes. My netgear router is on the latest firmware version V1.1.00.26_1.00.26NA. The problem happens on a windows 7 desktop, windows 10 laptop and windows 7 laptop. Plus these same computers have the same issue with a new Samsung wireless printer. I have the default router settings with no custom configurations or changes. Finally no firewalls are on the computers. Final thing to note, none of these system ever disconnect from the internet. during it all internet from every system works perfectly.

[Glowfish]

That does sound like a very strange scenario especially as the devices apparently have Internet access. Just some clarification questions. Are you pinging these devices and other computers from the same PC? Did you try pinging the devices from different PC's? Are any of your PC's or devices using fixed IP addresses as opposed to DHCP? Are you sure you don't have any network "loops" where one Ethernet cable is plugged from the router back into the router or hubs and switches connected together into loops? Do any of the devices (such as the laptops) have both a cable and Wifi links to the router at the same time?

[spidy_web]

I have tried doing the ping from multiple computers both return the same issue.  Everything uses DHCP.  I'm pretty sure there are no network loops, but I do have a second switch (used same setup for several years with no problems before).  We did move to a new house so I will retrace that to make sure I didn't cause a loop back.  the laptops all use wifi and don't have jacks close by.  The main PC that drops off is on a jack as it is a desktop and has no wifi.  I don't recall trying to ping from that box when the other doesn't see it.  I will test that also.  When the problem happens I use teamcenter to remotely control the desktop which works just fine, even from the box that can't ping it.

[Glowfish]

From your last post you mentioned you could still connect to other devices using some sort of remote desktop software even though you could not ping that PC in question? Can you use your devices on the network but just can't ping them?

[spidy_web]

That is correct, the setup I have is a shared printer on a desktop.  The other computers (all laptops) often cannot see the desktop and even sending a ping to the IP address fails.  But going to the desktop through teamviewer works fine and the desktop can see the internet fine.  In fact there is a media drive on the same box and using Plex my Roku players never have an issue. Even when the other laptops can't see the computer.  It's like the desktop decides it doesn't want to play on the LAN, but says internet is just fine for me.  The desktop is Windows 7, but I upgraded it to 10 for a while to try and fix the issue with no change.  I've also tried new laptops to the house and they excibit the same behavior.  Only comon factor is the router (extra switch is only used for two roku's).  I will trace wires when I get home after work and report.

[spidy_web]

I double checked all the cables to both the router and switch and nothing is looping.  In fact the router, which has my wifi signal also has the desktop plugged into it.  The second switch is just used for roku devices.

[Glowfish]

Since you say you have no fixed IP's anywhere that suggests there isn't sudden IP conflicts when the router updates everyone's IP. There are no network loops which might confuse the routing. Apparently you can still use the devices just not ping them suggests only ICMP packets are getting blocked but you mentioned you did not have any firewalls active.

Unfortunately I am fresh out of ideas. Perhaps the next time you suddenly can't ping devices, unplug one device at a time, check to see if anything comes back just to check that none of the devices are messing up the LAN.

The switch is assuredly a switch? Not a second router that you are just using as a switch?

[spidy_web]

Thanks, I will try that next time it happens and double check through the netgear interface what it shows for my IP address for all devices.  If there was a conflict I would expect one to still respond, but computers can be tricky.  The second switch is just a switch, simple 4 port daisy chain switch with no wifi or anything else.