First Make sure your outside IP points to your local IP.
Lets say you purchase a domain or using a dynamic name resolver,the Cname must point to your local ISP fixed IP.If your local IP provided by your ISP is Dynamic,you definitely have To use some form of DDNS like TZO.
How do you know your local Public IP. Go to https://grc.com then chose services and shields up
Your IP is normally at the bottom and somewhere in the text.
There are others like Can You see me etc. but I like grc.
Now you should have done that step already since you are familar with linux
The Next step is to fixed the Double Nat'ed
Double Nat'ed
If you Are behind a firewall and then a router then you need to make sure the firewall has an IN definition to the Router.
Make sure the router have port forward for port 443
Bit As I said you are Double Nat'ed some where if name resolution is okay
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