I'm installing on ubuntu 16.04 LTS server and after reboot I cannot even log in. I've since tried this on Ubuntu Mate & DOcean's ubuntu 16.04 and all will not let me log in after installing PiHole nor will the web service even show up. Is it something with the AMD install scripts that's bricking it?
Long time user & thankful for my pi-hole & the community.
Could you try installing again? We actually released another version to fix some issues.
Thank you so much for your time & reply. I'm not near my pi to use ubuntu mate w the holiday but I did just try to spin up a DO droplet with these exact steps and it still bricks the instance.
Spin up 512 16.04 droplet
tick to use my ssh key only
ssh root@ipaddress with ssh key
On setup choose opendns
Choose droplet ip as IP address AND gateway
it gives me temp password
sets up great.
Go to pi.hole.ip/admin & login
...everything works great & all functions work
Then I reboot server and cannot root@pihole ip - "port 22: Operation timed out" and the webserver wont come up either. Bricks. 
Thank you again for your time & have a great holiday.
I did exactly what you described on the cheapest Ubuntu DO droplet (Frankfurt) and everything works just nicely.
The only difference is that I don't use SSH key but regular password login. Have you tried standard password authentication as well?
Please go to DO and at your droplet console screen, type netstat -tulpn and that will let us know if the sshd daemon is listening on port 22. Also, if you can get a systemctl -i status sshd so we can see the status of the ssh daemon.
Unable to replicate, but that doesn't mean it's not happening. A timeout is different than a refusal, for ports to timeout then there may be a firewall in the way.
We do have a few tools to troubleshoot it, first would be ssh -vvv root@<IP> to get a verbose conversation of the attempt at ssh, and then also a curl -i <IP> to see if you are getting the X-Headers that we would expect to find from a Pi-hole installation.
And lastly, I we have specific logic to detect what the upstream gateway should be, so changing the gateway to the IP address of the Pi-hole will block that Pi-hole from being able to route traffic out the egress interface and most likely is the cause of the timeouts, there just isn't anything there to listen to the packets.
So apologies for doing it wrong — yes, having the pi-hole and y'alls' amazing expertise not set the gateway for me was where I went wrong. Setting that gateway did somehow block me from logging in... So yea, it's obvious I'm an appreciative fan & pi-hole supporter and not an expert.
All works fine if you set the ipv4 as the droplet's IP and have pi-hole automagically set the gateway.
Thank you for your time @DanSchaper, @jacob.salmela & @DL6ER.
Hope y'all had a great holiday & enjoy the new year. I look forward to contributing to the community & to y'all more donation-wise.
-me
*I will mention though setting both the ipv4 AND gateway to droplet IP on a debian droplet still allows me to login after reboot though that is why I came here after seeing the difference. ...didn't want y'all to think I completely wasted time.