Bitcoins were sent to the correct address, but did not arrive, and Bitcoin Core wallet, information is: Unconfirmed. Sent to - How do I solve this problem? Thank you?
In the Bitcoin network, transactions are confirmed by including them into blocks, which are then permanently stored in the blockchain.
Blocks are mined, on average, every 10 minutes, but this is actually a random Poisson process, just as you can say a given piece of uranium will emit an alpha particle every 10 seconds on average. Sometimes, blocks will be found within the same minute, sometimes it may take an hour.
Blocks also have a maximum size, which is now pretty close to the transaction volume of Bitcoin at the moment. Rational miners who receive more transactions than will fit in their block, will mine higher fee transactions before lower fee transactions. If the transaction fee you paid was very small, your transaction will eventually confirm, it will just take much longer (up to a few hours).