Post-Merge Devnet: Lighthouse beacon node waits for deposits and Reth shows no peers / no beacon connection

[DevJSter]

Hi all, I'm trying to set up a local Ethereum devnet with a custom chain config using Reth as the execution client and Lighthouse as the beacon client, but running into a couple issues I could use help untangling.

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🖥️ Reth command:

reth node --datadir "./data" --http --ws --port 30303 --http.api all --chain config.json

Logs:

2025-05-15T07:13:48.891702Z  WARN Post-merge network, but never seen beacon client. Please launch one to follow the chain!
2025-05-15T07:13:51.894106Z  INFO Status connected_peers=0 latest_block=0
...

So Reth is waiting for a beacon client to show up, but never sees one.

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🖥️ Lighthouse command:

lighthouse beacon_node \
  --testnet-dir ./config \
  --datadir ./lighthouse-data \
  --jwt-secrets ./data/jwt.hex \
  --execution-endpoint http://localhost:8551 \
  --disable-packet-filter \
  --port 9000 \
  --http \
  --http-address 0.0.0.0 \
  --disable-upnp \
  --disable-deposit-contract-sync

Logs:

Waiting for more deposits, valid_deposits: None, total_deposits: 0, min_genesis_active_validators: 32
...
No new deposits found, total_deposits: 0

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Problem Summary:

• Reth warns that it hasn't seen a beacon client yet
• Lighthouse keeps polling for deposits, finds none, and genesis isn’t triggered
• There’s no genesis.ssz / genesis state created, and no active validators yet

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Questions:

1. Am I missing a genesis generation step (like running a lighthouse create-testnet equivalent — which doesn't exist in latest builds)?
2. How should I create the testnet-dir with all required files (config.yaml, genesis.ssz, deposit_contract_block.txt, etc) for a local post-merge devnet?
3. Should I pre-generate deposits and genesis using some separate tool or script compatible with Lighthouse + Reth?
4. Or is there an updated recommended workflow for running a local devnet on post-merge clients now that Eth1 deposits aren’t a thing for custom networks?

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Would love any guidance or working examples for setting up a local Reth + Lighthouse devnet post-merge.

Thanks a ton in advance.

[DevJSter]

@anyone ?>