In principle, your (home) network and no device connected to it should be accessible from the internet. Fortunately, you can easily check whether that is indeed the case, even comfortably from your tablet, for example.
Actually, no device connected to your home network should be accessible from outside via the internet. Unless you have consciously arranged that via a port forwarding action to, for example, (a service of) your NAS. It is also not wise to make your router accessible via the internet. Many routers offer that option and it sometimes sounds enticing. But you have to set a twisted strong password. More advanced routers also offer the possibility to share, for example, a connected storage medium. This gives the same router NAS functionality. Can be useful, but in such cases make sure you do that with a router that you know for sure that there are regular security updates. Unfortunately, that is not really the case with many routers.
Check your gates
There is a handy website to check from the outside what ports (or – literally – access ports to devices and services running on your home network) are open. Visit www.grc.com with your browser. Tap or click there Shields Up!!. Scroll down a bit and click on the link Shields Up!. On the now opened page you will see your internet IP address listed a bit lower, always handy to know. Press the button Process to proceed to. click on File Sharing in the menu bar with available vulnerability tests. This test should always give a 'clean' result under all circumstances. If NetBios appears to respond, then there is something very fundamentally and seriously wrong with your router's security settings! click on Common Ports for a quick port scan of ports known to be problematic. Ideally, everything here should be on Stealth, where Closed is also a relatively safe option (but with which you indicate that your IP address is active). In some cases it is impossible to get all ports on stealth, for example if your provider uses a port for service purposes. However, it should at least have a 'Closed' status. click on All service ports for an extensive (and therefore longer lasting) port scan. If you find open ports (red colored blocks) somewhere in this overview, then that is a serious problem - unless done very deliberately. And so you need to find out what settings are wrong in your router. A good starting point is to carefully check the firewall settings of that device.
In case of crazy results
Click on a non-green (or green...) colored block to get more information about the specific gate, which will put you on the track faster. As mentioned, sometimes you can't escape certain open ports on a provider router. It also sometimes happens that a router responds 'adaptively' and switches ports in stealth mode after a port scan. Issue of running the full scan again and see if anything changes.
