Simplify it first:

Go to "ipchicken.com" and write it down.

Make sure the service you want to connect to on your nas is running. I'm assuming you're able to log in to 192.168.0.5:80 and it possibly redirects to 192.168.0.5:443.

If you can be on your network and access either one via chrome or firefox, or whatever, keep reading.

Assuming your setup is like this:

Modem --> router --> switch --> nas

or

Modem --> router --> nas

If it's either one, open port 80 and 443 on your router and tie it to 192.168.0.5.

Go here: https://portchecker.co/

Pop in your IP and test for port 80 then 443.

If one or both are closed, you've got bigger issues. Restart everything first. Modem then router.

If the ports are open after the reboot, then start complicating your set up.