fallback 
The fallback Transport consumes multiple Transports. If a Transport request fails, it will fall back to the next one in the list. Wraps Viem's fallback Transport.
Import 
ts
import { fallback } from '@wagmi/core'Usage 
ts
import { 
  createConfig, 
  fallback,
  http,
} from '@wagmi/core'
import { mainnet } from '@wagmi/core/chains'
export const config = createConfig({
  chains: [mainnet],
  connectors: [injected()],
  transports: {
    [mainnet.id]: fallback([ 
      http('https://eth-mainnet.g.alchemy.com/v2/...'), 
      http('https://mainnet.infura.io/v3/...'), 
    ]) 
  },
})