You're most likely using an outdated version. Thus, please upgrade to the latest version:

https://monero.stackexchange.com/questions/6056/how-do-i-upgrade-my-software-to-v0-11-0-0

Is there any reliable Monero wallet for Android which keeps the private key in your device?

Yes.  There is Monerujo.  Open source light wallet for android.

I use it.  I bought a Ledger Nano S and a Cryptosteel with it.

Do your own due diligence.

https://github.com/m2049r/xmrwallet/releases

Three things i like best about Monero
1. Easy and profitable to mine
2. Great store of value
3. Gives me peace of mind if i needed to do a private transaction for wharever reason, its easy to do and readibly at hand.

This is great timing to take risk on this project I hope this will go to the moon.

This is slightly off topic but relates to monero by decentralization and privacy so I give myself a licence to ask here.

Is there any ready fuctioning decentralized Internet available?

I found these.
https://blockstack.org/
https://maidsafe.net/

But they seem to be beta this and beta that and under of development. Ready not yet and so on.

So if I would like establish for example a site for monero where domain and data storage and such are decentralized the way that they cannot be taken down by TPTB, how can I do it? Is there tecnology available?

And such easy way that I do not has to fight with it for weeks. Like such that ordinary CLI GUI linux crypto oriented user can do it.

"Pirate Bay Founder’s ‘Njalla’ Offers Anonymous Domain Registration" - Monero Accepted: Just recently the founder of the notorious torrent website the Pirate Bay launched a new privacy-centric domain registration service called ‘Njalla.’ This type of service has become a hot commodity lately as domain names are hard to obtain without providing identity details to the registrar. https://news.bitcoin.com/pirate-bay-founders-njalla-offers-anonymous-domain-registration-for-bitcoin/