I'm using Hardhat to deploy a smart contract, it's deployed successfully to Polygon, but when trying to deploy into RSK, it fails with -

```bash
$ npx hardhat run scripts/deploy.js --network rsk

SocketError: closed
    at Socket.onSocketClose (./node_modules/undici/lib/client.js:967:31)
    at Socket.emit (events.js:400:28)
    at TCP.<anonymous> (net.js:675:12) {
  code: 'UND_ERR_SOCKET',
  socket: {
    localAddress: undefined,
    localPort: undefined,
    remoteAddress: undefined,
    remotePort: undefined,
    remoteFamily: undefined,
    timeout: undefined,
    bytesWritten: 209,
    bytesRead: 125
  }
}

```

In `hardhat.config.js`, RSK is defined as following -

```
    ...
    networks: {
        rsk: {
            url: '...',
            accounts: [...],
            timeout: 120000,
        },
        polygon: {
            url: '...',
            accounts: [...],
        },
    },
    ...

```

1. It happens on two different synced local [RSKJ](https://github.com/rsksmart/rskj) nodes, same result - but works on the public `https://public-node.rsk.co` node.
2. It worked in the past on my local nodes, nothing changed since! (that I know of)

So what could be the issue with my local RSK nodes?