Testnet full node is launched & working but not syncing

I’ve setup from source and launched the Testnet full node using this manual - Run a Sui Full node | Sui Docs, but when I’m using following command:
curl -X POST -H 'Content-Type: application/json' -d '{ "jsonrpc": "2.0", "id": 1, "method": "sui_getTotalTransactionNumber", "params": [] }'
…it shows:
So looks like my node is working, but not syncing.

Could anyone help me to fix the issue?


Check again in : Node Checker

Thanks @Pyzz , but I don’t want to open ports
Also, why I should use any external tools instead of using native commands?