First of all, open the extension and select the drop-down menu that says Main Ethereum Network.
It descends between the different pre-established networks; and select custom RPC.
And then enter the information in the form as it appears here:
Network Name: Polygon
New RPC URL: https://rpc-mainnet.maticvigil.com/arrow-up-right
ChainID: 137
Symbol: MATIC
Block Explorer URL: arrow-up-right arrow-up-righthttps://explorer.matic.network/arrow-up-right Congratulations, you already have the Polygon network (MATIC).
Last updated 4 years ago