Add Robinhood Chain to your wallet

MetaMask, extension

The button works. If you would rather do it by hand: Settings, Networks, Add a network, then Add a network manually at the bottom of the list – the top of that screen is a list of chains MetaMask already knows, and this one is not on it. Fill the five fields above exactly and save.

MetaMask, mobile

The in-app browser has the same provider, so opening this page inside it and pressing the button works. From the app instead: Settings, Networks, Add network, Custom networks. The mobile form rejects an RPC it cannot reach, so if it refuses, the endpoint is the thing to check rather than the chain ID.

Rabby

Rabby maintains its own chain list and adds networks on demand when a site asks for one, so the button is the whole procedure. It also shows the chain in its switcher afterwards without a reload, which MetaMask does not always do.

OKX Wallet

Supports the chain natively – it should already be in the network list before you add anything. Use the button only if it is not.

Coinbase Wallet

The extension answers the same method and the button works. The mobile app accepts custom networks through its own settings rather than from a page.

Trust Wallet

Settings, Networks, then add a network manually with the fields above. Trust does not expose the add method to websites in the same way, so the button is unlikely to do anything there – this is a manual one.

Rainbow, Phantom and the rest

Any wallet that injects an EVM provider will answer the button. Wallets built around another chain – Phantom being the common case – support EVM chains through a separate mode rather than by default, and whether this one appears depends on their own list rather than on anything here.

Could not fetch chain ID

The wallet tried to reach the RPC and did not get an answer it could use. Usually the URL has a stray character, or a corporate network or extension is blocking the request. Paste the RPC into a browser tab: a bare POST endpoint will not render a page, but a total failure to connect looks different from a rejection, and that difference is the answer.

The chain ID does not match

MetaMask checks the ID you typed against the one the endpoint reports and refuses when they differ. The endpoint here reports 0x1237, which is 4663 in decimal. A wallet that wants hexadecimal and receives 4663 will report exactly this error.

The network already exists

Something added it before – another site, or an earlier attempt with a different RPC. The wallet will not create a duplicate, so edit the existing entry rather than adding a second one, and check its RPC matches the one above.

Circuit breaker is open, or rate limited

These are the public endpoint under load, not a fault in your setup. The public RPC is sized for wallets rather than for applications polling it, so an indexer or a bot hitting it will trip this and a wallet sharing the endpoint sees the result. Wait, or use a dedicated endpoint for anything automated.