How to Add a New Network like Polygon or BSC to MetaMask? (Multi-Chain Guide)

Understanding Network Configuration in MetaMask

1. MetaMask operates as a bridge between users and blockchain networks beyond Ethereum Mainnet. Each supported chain requires specific RPC endpoints, chain IDs, currency symbols, and block explorer URLs.

2. Networks such as Polygon and BSC are not pre-loaded by default. Users must manually input configuration parameters to establish connectivity.

3. Incorrect values for chain ID or RPC URL will result in failed transactions, balance mismatches, or inability to interact with dApps.

4. The network name field is user-defined—this label appears in the MetaMask network dropdown and does not affect functionality.

5. Custom network settings are stored locally in the browser extension or mobile app, meaning they persist across sessions but do not sync automatically across devices unless wallet backup is restored.

Step-by-Step Addition of Polygon Mainnet

1. Open MetaMask and click the network selector dropdown located at the top center of the interface.

2. Select Add Network and then choose Add a network manually.

3. Enter Polygon Mainnet as the network name.

4. Input https://polygon-rpc.com/ as the New RPC URL.

5. Set Chain ID to 137, Symbol to MATIC, and Block Explorer URL to https://polygonscan.com/.

Integrating Binance Smart Chain (BSC)

1. Navigate again to the network selector and select Add Network → Add a network manually.

2. Assign the network name as BSC Mainnet.

3. Use https://bsc-dataseed.binance.org/ for the RPC URL.

4. Specify Chain ID as 56, Currency Symbol as BNB, and Block Explorer URL as https://bscscan.com/.

5. Confirm submission—MetaMask will validate the connection before saving the configuration.

Security Considerations When Adding Networks

1. Always verify RPC URLs from official project documentation—not third-party forums or unverified social media posts.

2. Public RPC endpoints may throttle requests or log IP addresses; avoid sending sensitive data through them without understanding their privacy policies.

3. Never enter private keys or seed phrases when configuring networks—MetaMask never asks for these during setup.

4. Double-check chain IDs against authoritative sources like Chainlist.org or the official blockchain GitHub repository.

5. If a newly added network shows zero balance despite known holdings, confirm that the correct network is selected and that token contracts are deployed on that chain.

Troubleshooting Common Network Issues

1. Transaction stuck in pending state? Check if the gas price is too low for the target network’s current congestion level.

2. “Unknown network” error after adding? Revisit the Chain ID—it must match exactly, including decimal vs. hexadecimal representation.

3. Token balances not appearing? Ensure the token’s contract address is deployed on the selected network and add it manually via the “Import Tokens” function.

4. MetaMask fails to detect custom network? Clear browser cache or restart the extension—corrupted local storage can interfere with network registration.

Frequently Asked Questions

Q: Can I add testnets like Mumbai or BSC Testnet using the same method?A: Yes. Replace the RPC URL, Chain ID, and Block Explorer with testnet equivalents—for example, Mumbai uses Chain ID 80001 and RPC URL https://rpc-mumbai.maticvigil.com/.

Q: Why does MetaMask show “Not connected” even after adding a network?A: This indicates the RPC endpoint is unreachable or misconfigured. Try alternate RPC URLs provided by the network’s official docs or community-maintained lists.

Q: Do I need separate wallets for each network?A: No. Your Ethereum address remains identical across all EVM-compatible chains. Funds and tokens exist only on the chains where they were sent or minted.

Q: Is it safe to use third-party RPC providers like Infura or Alchemy for custom networks?A: Yes—if sourced directly from their official documentation. Avoid shortened links or RPCs shared in Telegram groups without verification.