Take notebook from Brazil to EU?

Have a notebook in Brazil, which I will soon take to the EU.

Can there be problems in use, e.g. Online banking?

No. Why should that be so?

Do not forget to tell the customs.

That's clear with the customs.

Have heard something from other IP, so my question.

You always get another IP from the provider when your router / modem logs out. No matter which country it is you are applying for a static, but even that would not matter.