WLAN set up without connection?

I moved into my first apartment and I would like to set up WLAN, but have no DSL connection in my apartment. I do not know so well and wanted to ask what there are alternatives, if you can set up a router without a connection? I would like to have Wi-Fi for my phone, laptop and possibly other devices. If you have experience you can gladly recommend a provider

Of course, you can use a wireless router without a connection, but then you can't use the devices to the Internet. For this you need then an Internet connection.

A WLAN is initially independent of an Internet connection. If you do not mind the radiation exposure, then you can also get an internet connection via mobile phone. http://www.congstar.de has e.g. Such an offer.

I would ask your neighbors, if you do not leave for 5 euro a month with the Internet.

Wi-Fi ≠ Internet

Of course, you can set up a Wi-Fi-enabled router and make you a Wi-Fi for your devices available.
The devices can then communicate with each other, but do not come to the Internet, because this connection does not exist.

However, if you want to set up an Internet connection without having an appropriate connection, you could use the mobile network. There are routers in which you can put a SIM card. So you could use such a router and conclude a mobile phone contract for the Internet. But first check how good the reception is with you.

Internet without internet service is not.

You already need an internet provider.

Choose one, check the availability (DSL, cable, LTE, …)

IMPORTANT: Pay close attention to the minimum contract period and the monthly installments after 12 months or after 24 months, then they will be really expensive.

Here is a comparison portal: https://www.verivox.de/lp/sea/dsl/

That would be an alternative: https://freifunk.net/