#StackBounty: #gateway #route #arp "No route to host" until "ping" or "route"

Bounty: 50

I have two computers in one WiFi network:

  • A – client
  • B – server

Sometimes (once in ten times) after B reboot I am unable to ssh from A to B:

$ ssh 192.168.201.128
ssh: connect to host 192.168.201.128 port 22: No route to host

When I try to ping it, I get:

$ ping 192.168.201.128
PING 192.168.201.128 (192.168.201.128) 56(84) bytes of data.
From 192.168.201.133 icmp_seq=1 Destination Host Unreachable
From 192.168.201.133 icmp_seq=2 Destination Host Unreachable
From 192.168.201.133 icmp_seq=3 Destination Host Unreachable

ARP might be the issue:

$ arp
Address                  HWtype  HWaddress           Flags Mask            Iface
_gateway                 ether   70:4c:a5:a7:c2:57   C                     wlp2s0
192.168.201.128                  (incomplete)                              wlp2s0

I was trying to fix it like this:

$ sudo arp -d 192.168.201.128
$ arping -c 10 -I wlp2s0 192.168.201.128
ARPING 192.168.201.128 from 192.168.201.133 wlp2s0
Sent 10 probes (10 broadcast(s))
Received 0 response(s)

no effect 🙁

I can only workaround the issue by plugging in monitor and keyboard to B (server) and doing either:

1) ping A (client)

OR

2) typing “route” in terminal

Then everything goes back to normal.

Any idea why this might be happening?
My guess is that B sometimes doesn’t discover gateway correctly. I am unable to verify this, because when I type “route” in B terminal everything goes back to normal.

Side notes:

  1. There is no firewall on B (server)
  2. A (client) is Ubuntu 18.04 Desktop
  3. B (server) is Ubuntu 16.04 minimal (maybe missing some important package for arp/ auto gw discovery?)


Get this bounty!!!

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