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I have a PC on my network. It is configured with a static IP address, 192.168.1.110. It is connected via LAN cable directly to my router with IP address 192.168.1.1. The PC's gateway is set to the router's IP address.

From another PC, IP address 192.168.1.2, also connected to the router over LAN, I am unable to ping 192.168.1.110 (destination host unreachable). I am also unable to remote into it.

From my Android phone, using Microsoft Remote Desktop, and with the phone connected to the router via WiFi, I am able to remote into 192.168.1.110. Here is a screengrab from my phone:

When I open my router's status page, I see the target PC's MAC address on the clients tab three times: Once under Active Clients, with the expected static IP address, and twice unexpectedly under the dynamic clients tab, with different IP addresses, even though the PC is not configured to use DHCP:

What is going on here that I can't reach .110 from .2?

EDIT: I am also unable to ping or remote into the two dynamic addresses, .127 and .128.

EDIT 2: Additional info

.2 Network Config

.2 ARP Table

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  • well, since it says destination host unreachable, its is likely that the problem is on the .2 host, rather than the .110 host. what does its routing table look like, does it have a default gateway set, and is its subnet mask the same? disregard the DHCP page on your router, its just telling you that that mac has previously had a DHCP lease. most of the time, a dhcp server is not made aware that a host is offline or switched to static, since the host never tells the server about the change so the server just displays the old lease. also adjust your dhcp pool to exclude the static IP (.110).
    – Frank Thomas
    Commented Oct 20, 2016 at 14:21
  • if you run arp -a on the .2 host, what IP does it expect that MAC to have?
    – Frank Thomas
    Commented Oct 20, 2016 at 14:49
  • Frank, I'm not sure that it is the .2 host. If I fire up my work laptop and connect to the wifi, I can't connect to or ping .110 either. Nevertheless, additional info added above.
    – staterium
    Commented Oct 20, 2016 at 15:11
  • arp looks fine for ,110 (though its likely incorrect for .100/101).
    – Frank Thomas
    Commented Oct 20, 2016 at 15:14
  • I see you have other hosts in this LAN too (1.3 and 1.101). Can they reach 192.168.1.2?
    – VL-80
    Commented Oct 20, 2016 at 15:20

1 Answer 1

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The fact that the MAC address associated with IP address 192.168.1.110 via a static configuration is ALSO is associated with, not just one, but, two, DHCP-assigned IP addresses cannot be overlooked. Unless the device at 110 has three NICs legitimately holding the three IP addresses (.110, .127 and .128) then there is a form of route cache poisoning in effect. Although it is difficult to say exactly why your ping attempt is returning a destination host unreachable, it is not entirely unexpected considering the router's uncertainty concerning the MAC hardware's true IP assignment. Therefore by deleting those two erroneous DHCP leases (or otherwise eliminating them from the router's view as you did when you transferred the IP entry to the other router) you should be able to restore normal ICMP (ping) visibility between the two machines (.2 and .110). Good luck. Remember, unless the device has multiple ethernet interfaces, there should be a one-to-one correspondence between the MAC address and the IP address. Ensuring this should clear up the problem.

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