Why can't every Kaspa node be used for mining or wallet operations?

Not every Kaspa node is suitable for mining or wallet use because those functions require the node's RPC port (16110) to be open, and many nodes do not expose it. Kaspa nodes have two relevant ports: port 16111 handles p2p synchronization — the process of keeping a node's copy of the blockchain up to date — while port 16110 is the RPC port that mining software and wallets need to communicate with the node. DNS seeders are designed to supply addresses for syncing purposes only and do not guarantee that any given node has its RPC port open. This matters because connecting your miner or wallet to a node without an open RPC port will silently fail, so verifying port availability before you configure your software saves significant troubleshooting time.