Why are my transactions included after 2 blocks?

It might not be a geolocation issue. Typically, a block is created and sealed in under 500 milliseconds. A validator publishes a block and then waits for about 2 seconds to publish it. Due to propagation latency, the transaction might get included in the n+2 block. I'm still looking into this and will update you once I have more information.

Make sure that you are connected to enough peers and that your node's network connection is stable. If latency is an issue, it might be related to your node's connectivity or synchronization speed.

Your transactions being consistently included in block n+2 rather than the next block is likely due to network propagation delays rather than a fundamental issue with your node. On networks like Polygon, blocks are typically created and sealed in under 500 milliseconds, and validators wait about 2 seconds before producing the next block. Due to network latency, your transaction might not reach a validator in time for inclusion in n+1, causing it to appear in n+2 instead. This can be influenced by peer connections, block propagation speed, transaction relay timing, and overall network conditions.

To diagnose and fix this issue, consider the following steps:

1. Check Your Peer Connections

Your node depends on peers to receive new blocks and relay transactions. If your node has too few or slow peers, transactions may take longer to propagate, causing delays.

You can check the number of peers connected to your node using:

geth attach http://127.0.0.1:8545
> net.peerCount

For Ethereum-based nodes like Polygon, this command will return the number of peers. If the count is low (e.g., fewer than 10), your node may be poorly connected. To add more peers, manually include them using the admin.addPeer() command:

> admin.addPeer("enode://your-peer-node")

If your node is not well-connected, consider adding bootnodes or increasing your max peer connections in your client configuration.

2. Evaluate Network Latency and Block Synchronization

Even with enough peers, network latency can delay block reception. You can measure the time it takes for your node to recognize new blocks by running:

> eth.syncing

If your node is slightly behind, it means it is receiving blocks later than the rest of the network. Compare the latest block on your node with a block explorer like PolygonScan:

> eth.blockNumber

If there’s a significant delay between your node and the network, consider optimizing your connection by hosting your node on a lower-latency VPS or using a faster internet connection.

3. Monitor Transaction Propagation

Your transactions may not be reaching validators fast enough. Use the mempool to see if your transaction is propagating efficiently:

> txpool.inspect

If your transaction appears in the local pool but isn't being included in the next block, it might not be reaching enough peers quickly. You can use tools like Mempool Explorer to verify if your transaction is visible across the network.

To manually rebroadcast a pending transaction, use:

> eth.sendRawTransaction("0x-your-transaction-hash")

This ensures the transaction gets re-broadcasted to more peers, increasing its chances of inclusion in the next block.

4. Adjust Gas Fees if Necessary

Although gas fees might not be the primary cause, lower gas fees can sometimes lead to delays. Compare the gas fees of your transactions with those included in n+1 blocks:

> eth.getTransaction("0x-your-tx-hash")

Look for the gasPrice value and compare it with recent transactions in the latest blocks using:

> eth.getBlock("latest", true)

If needed, resend the transaction with a higher gas fee using a replacement transaction (if it's still pending).

5. Investigate Validator Selection and Consensus Mechanism

If your blockchain operates on Proof of Stake (PoS), validator selection can influence transaction timing. Some validators have faster block propagation than others, meaning transactions that don’t reach them quickly might be delayed.

Check which validator included your transaction by fetching the block details:

> eth.getBlock(n+2, true)

This will return details of the validator that processed your transaction. If the same validators are frequently processing your transactions, your node may be connected better to specific validators while missing others.

If the problem persists, you might not be the only one experiencing it. Consider discussing your issue in the Polygon Community Forum. Other node operators might have encountered similar behavior and could provide additional insights.

The issue likely comes down to transaction propagation speed and network latency. If your node isn’t broadcasting transactions quickly enough or receiving blocks with slight delays, it can cause transactions to land in n+2 instead of n+1.