You can access you admin on the dev website. https://www.avantalarm.com/dev/index.php/admin
I don't know what can cause this. Maybe it's a custom extension. I saw that you are using BalkeTechnologies_StoreMaintenance that has a custom router. Could  be that.
Anyway you now can acccess the admin on the dev website.
[Edit]
Also the base url should be changed in core_config_data.

Access admin for sub directory website
I am considering building my next PC into a server rack case, the reason is I am getting a server cabinet and will be putting in a few servers in it.  It will be in my room where I use my main PC as well and in my case it just makes sense to build my next PC into this cabinet/rack.  

So my main concern, will I be able to extend my mouse, keyboard, and 2-3 monitors 10-15 feet across a room from my server rack to my desk?
