Recently the Polygon blockchain has seen unprecedented activity. While it has fared well, the RPC endpoints serving data are often overloaded, due to everyone using the same services. If you are experiencing erratic site loading, transaction delays/failures, or other unexpected behaviour, you may be experiencing an RPC issue.
In order to improve your experience, you can switch to another RPC server.
For Metamask this can be done by navigating to:
Settings > Networks > (Your Polygon Network)
From there, update the New RPC URL value.
Alternative RPC servers:
The Chain ID is always 137: do not change this, or any of the other settings.
You may edit the existing Polygon MATIC network connection, or add a new network such as "Polygon 2". After updating the RPC address, confirm whether you are able to connect to Polygon and that your balance(s) display correctly.