Do not download all that software just for store coins. I don't think it is the safest , and it is a lot of work. Unless you are someone interesting in learning all those technologies,  I wouldn't store my coins in so many softwares.


You have one seed for all coins. It is not stored anywhere,  just in your device and your piece of paper back up.


It is safe to use ledger nano. Pmalek already answered you those questions.

You are a new comer. The safest way is to buy a hardware wallet from the manufacturer.  I suggest only ledger or trezor. Do not buy from third party

Storing seeds and private keys digitally is not recommended. You should write it down on paper and store it in 3 separate geographical locations if possible. It's much easier to make backups of seeds than it is of private keys. Maybe it's worth considering using Electrum for your Bitcoin because with that app, you get a 12-word seed to back up. That's unless you are insisting on having a full-node client. If you have to use USB drives for sensitive data (again, not recommended), at least encrypt and/or password-protect the files.

Your wallets are not offline if your computers are connected to the internet and you use them to sync and download the latest blocks. Did I understand correctly that you are planning to use 4 different PCs for each of your wallet or are we talking about 4 SSDs on the same computer? And will those computers be used for any other activities besides holding your software wallets and syncing with the blockchain? Are they clean with freshly installed OSs or have you use them in the past for other stuff?

Seeds and private keys remain on the device all all times. Ledger uses secure element chips in their hardware wallets, and sensitive data doesn't leave those chips. The seed is only shown to you once during the setup process. Once that is done and you have made a backup of it, you can't see it ever again. You can't see the seed in the native Ledger Live app.

No. Wallets that generate BIP-39 compatible seeds (like Ledger in this case) can be recovered in other software or hardware wallets. If your device breaks, Ledger ceases to exist as a company, or your computer where the software/hardware is used malfunctions, you have your seed backups to rely on. The Ledger is just a hardware device that keeps your private keys in the secure element and signs transactions for you.  

Keyloggers don't swap addresses. They record and log your activities, like the things you write on your keyboard, they can take screenshots of what is on your screen, etc. This data gets stolen and sent to a malicious party. But like I mentioned above, your recovery phrase is never visible in a software environment, it never leaves the safety of the device, which means there is nothing for the keylogger to log. You also can't view or copy your private keys because they are also always on the secure element. So again, the keylogger has nothing to steal.

Clipboard malware is a different threat though. In theory, they can swap your legit address for one that belongs to a hacker. But that happens on a software level. When you make a transaction with a hardware wallet, all the information has to be checked and verified on the screen of that hardware device. Your malware can infect your computer, but I have never heard of a clipboard malware that can infect and modify the transaction details that are shown on the screen of your hardware wallet. Always confirm that the information is identical to what the Ledger shows. If you need to send a transaction to someone and you receive an address to pay to, a clipboard malware can replace that address when you copy it. When it's pasted into a software it can be a different address. It's your job to check that the pasted address (that will receive the coins) as well as the amounts and fees match with the one the other party gave you. If they don't, don't make the transaction. A hardware wallet can't protect you in this particular situation. If the other party makes a similar mistake and sends you the wrong BTC address, it's their fault.  

When we are talking about Ledger hardware wallets, you can't. The before-mentioned secure element chip is not open-source, which makes the firmware not open-source and the whole product closed-source.

This is not a cold wallet. This is the recipe for losing your coins without understanding how that could be possible. It has happened before. As said, cold storage should absolutely never go online after the address was set up in it. The cold storage doesn't even need to be synchronized with the blockchain. You should really read more about cold storage.


Do you by chance store the blockchain onto an external disk? If so, your problem may be caused by the disk disconnecting (bad data cable/contact or insufficient power sent to the disk).

This is not a cold wallet. This is the recipe for losing your coins without understanding how that could be possible. It has happened before. As said, cold storage should absolutely never go online after the address was set up in it. The cold storage doesn't even need to be synchronized with the blockchain. You should really read more about cold storage.


Do you by chance store the blockchain onto an external disk? If so, your problem may be caused by the disk disconnecting (bad data cable/contact or insufficient power sent to the disk).

And it's just core that closes? Nothing else?

Have you got access to your debug.log in your data directory? Do you move the blocks and chainstate files once your database gets considered corrupted and do you have any antivirus running or anything that might use a lot of resources all at once (particularly memory)?