Try changing from :
proxy_pass http://240.93.0.27;
to
proxy_pass http://240.93.0.27:80;
Try visiting mydomain.com/test/ or
http://[your host ip here]/test/
if you see the page, that worked.
Point to note : make sure that there is something listening inside the container on port 80 ( For example nginx or apache). As you didn’t mention what port, the proxy_pass isn’t working.
I didn’t quiet understand what you mean by this :
I have a similar setup where I use upstream to proxy traffic from my host to the containers.
You can setup proxy rules to pass ssh traffic on different ports of your host ip to the containers to access them using iptables. (Maybe adding a device proxy as well, but I haven’t tried proxying ssh into containers using the proxy settings mentioned here