Why is my iPhone unable to join a network?

If you possibly mean a “Mobile Network” …

… contact your carrier for assistance.

Screenshots of what your router is sending to your device. Click or tap on Network, then in the bottom right corner on Advanced. This should show you a list of the router codes in yoour area (including those near to where you live.

If no codes are showing, click on the Wifi icon on the right-hand end of the tool bar. Below your preferred network

You should see something like this:

If you don't see a list, using a paper clip, push it into a tiny hole in at the back of the router and hold it there for 30 seconds. This should reset your router. All the nearby routers with a padlock icon are NOT usable.

By the way, if you should find yourself in hospital, you may be able to use the Personal Hotspot facility on your iPhone as a relay to a Macbook, for private browsing, or the hospital may have a free wifi link you can use, but they are not secure,, in other words, you could be hacked.