What can be the reason for random intermittent connections?

Question

I have been getting random intermittent internet connections on few particular devices. Let us call these PC1, PC2 and Mobile1.

PC1 and PC2 are wired connections and Mobile1 uses wireless connection.

Both PCs run Linux and I ran a test on Windows on same devices and it did not show the aforementioned problem. Pinging the router from any of the three devices shows significant packet loss (anywhere from 10-40%).

The thing is, nothing has changed, neither the router nor the system configurations and the problem started out of nowhere a few days ago. I can ping PC2 from PC1 or Mobile1 and vice versa successfully with no packet loss.

This cannot be a DHCP issue, since I have already tried setting various static addresses. And I do not think this can be related to the ISP either since the router is causing the problem(?). What could be causing this problem? Why did the router start dropping these packets out of nowhere.

Note that all other devices, wireless and wired, still work as they should.

Things I have tried:

• Setting a static address for all 3 devices: It made no difference
• Rebooting the router a lot of times

The network device models should not be an issue since the issue was not there a few days ago with same configuration

The diagram can be as simple as this:

PC1 (wired) -------------------
                               \
                                |
PC2 (wired)------------------Router
                                |
                               /
Mobile1 (wireless)-------------

Answer 1

Everything points to the router as the problem.

• if it were a lose or broken cable, you would get a normal response from Mobile1.
• You are pinging the router, not some address on the Internet, so the Internet connection is not the issue.
• PC1 and PC2 ping each other without packet loss, so the switch-part of the router seems OK.
• You do not seem to have WiFi issues, because your ping from/to Mobile1 to/from PC1 or PC2 are OK.

So the router is the most obvious suspect. So, next step is to look at the router. And there, the solution depends on the router. My ISP's router is completely configured by my ISP, so if I have such a problem on my ISP-router, I need to cal them and try to get some technical person. If you manage the router yourself, it will depend quite a bit on what router it is. The type (SOHO NAt-router or 'real' router) brand and possibilities on the router.

Answer 2

You state, "Pinging the router from any of the three devices shows significant packet loss (anywhere from 10-40%)." And then issue occurs both over WiFi and Ethernet. Is something keeping the router very busy, e.g., a neighbor using it intensively?

Use a tool such as Nirsoft's Wireless Network Watcher, or an alternative, to see who is using your bandwidth.

Also consider IoT -- have you added any devices recently? Not only do some consume resources, but they even send data back to the OEM!