Sometimes can't access device on local network

[Colin Law]

On 31 December 2017 at 12:13, Colin Law <clanlaw at gmail.com> wrote:

> I have an odd situation that occurs occasionally.  I have a conventional
> wired local network (192.168.1.nnn) with in addition some devices connected
> via wifi. The main router (192.168.1.1) is also the wifi hub.
>
> Consider three of these machines. A, B and C.  A and B are wired and C is
> wifi, all with fixed IP addresses.
>
> Normally all is well but occasionally I am not able to access C from A.
> When I ping it I get
> $ ping 192.168.1.85
> PING 192.168.1.85 (192.168.1.85) 56(84) bytes of data.
> From 192.168.1.92 icmp_seq=1 Destination Host Unreachable
>
> 92 is the device I am running on (A).
>
> However I am able to access B from A and also able to access C from B,
> which is particularly odd. So, even though I cannot ssh into C from A, I
> can ssh into B from A and from there ssh into C.
>

The plot thickens! I see now that C is not responding to arp requests. Any
machines that already have C in their arp table continue to be able to
communicate but any that do not cannot. Now I need to work out why it is
not responding.

Colin
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