why has ssh stopped working on my raspberry pi?

Question

I was able to ssh into my raspberry pi with no problem for some time.

Today, however, it has just stopped working and I don't know why.

Initially, I thought it might be a problem with my router's mDNS,

 😈   >ssh -l pi alexpi.local
ssh: Could not resolve hostname alexpi.local: nodename nor servname provided, or not known

but then I discovered that I couldn't ssh to the raw IP address either.

 😈   >ssh -l pi 192.168.86.130
ssh: connect to host 192.168.86.130 port 22: Operation timed out

The ssh daemon appears to be running okay on the pi ...

pi@alexpi ~ $ sudo service ssh status
● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled)
   Active: active (running) since Thu 2016-03-10 11:39:31 PST; 3min 43s ago
 Main PID: 546 (sshd)
   CGroup: /system.slice/ssh.service
           └─546 /usr/sbin/sshd -D

Mar 10 11:39:31 alexpi systemd[1]: Started OpenBSD Secure Shell server.
Mar 10 11:39:32 alexpi sshd[546]: Server listening on 0.0.0.0 port 22.
Mar 10 11:39:32 alexpi sshd[546]: Server listening on :: port 22.
pi@alexpi ~ $ 

Then I discovered that I can't even ping the thing.

 😈   >ping 192.168.86.130
PING 192.168.86.130 (192.168.86.130): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
^C
--- 192.168.86.130 ping statistics ---
5 packets transmitted, 0 packets received, 100.0% packet loss

This makes no sense because

• the pi is on the same wifi network as my laptop AND
• I am able to access the internet from my pi AND
• I am able to ping my laptop from the pi (however it does give a strange error before it succeeds in pinging)

Here's what the ping from pi to laptop looks like ...

pi@alexpi ~ $ ping 192.168.86.111
PING 192.168.86.111 (192.168.86.111) 56(84) bytes of data.
From 192.168.86.130 icmp_seq=1 Destination Host Unreachable
From 192.168.86.130 icmp_seq=2 Destination Host Unreachable
From 192.168.86.130 icmp_seq=3 Destination Host Unreachable
64 bytes from 192.168.86.111: icmp_seq=4 ttl=64 time=22.3 ms
64 bytes from 192.168.86.111: icmp_seq=5 ttl=64 time=44.6 ms
64 bytes from 192.168.86.111: icmp_seq=6 ttl=64 time=2.37 ms
64 bytes from 192.168.86.111: icmp_seq=7 ttl=64 time=89.0 ms
64 bytes from 192.168.86.111: icmp_seq=8 ttl=64 time=1.86 ms
64 bytes from 192.168.86.111: icmp_seq=9 ttl=64 time=137 ms
64 bytes from 192.168.86.111: icmp_seq=10 ttl=64 time=2.66 ms
^C
--- 192.168.86.111 ping statistics ---
10 packets transmitted, 7 received, +3 errors, 30% packet loss, time 9004ms
rtt min/avg/max/mdev = 1.869/42.971/137.810/48.562 ms, pipe 3
pi@alexpi ~ $ 

Something is clearly impeding connectivity, but I'm not sure what it is.
I'm not even sure if the problem is on the pi or with my wifi router?
I don't believe that I made any changes to either between the time that it was working and when it stopped working.

UPDATE: rebooting the pi did not solve the problem.
However, rebooting my wifi router did. (for now)
So the problem appears to be with my Google Asus OnHub router. Though, I am not certain exactly what the problem is.

Answer 1

If you have an Android phone or tablet lying around, install Fing scanner or NetX on it and use it to see if your Pi still has the same IP # (if it's even on line at all). If the IP # did change, be sure to edit your connection settings in your laptop's terminal app.

Answer 2

Somehow the Router problems existing too much !!!
I think you should assign static IP on your Pi for the best connection.
By the way, try to re-configure your Router DHCP Server for your laptop connection.
For example, the range 192.168.86.10 (max hosts : 50) will be for your laptop. Then you assign your Pi into static address that different from the laptop network range.

Pi# sudo nano /etc/dhcpcd.conf
Pi# sudo reboot