Right now, when graph-node starts, it does some checks against each RPC endpoint; if those checks fail or time out, graph-node will mark the chain as not working and not use it anymore. That will also make all subgraphs that use that chain fail at startup. If the problem with the endpoint is transient, the only way to get graph-node to use it again is to restart it (at the danger that now some other chain has a transient issue)

The code needs to be changed such that graph-node is much more tolerant to such transient issues and automatically retries using a chain that caused trouble during startup. As part of solving the issue, we should also produce documentation that describes what is expected of an endpoint before we will use it, and a graphman command that allows checking any given endpoint by going through its startup sequence. Additionally, there needs to be some way to figure out which of the configured endpoints graph-node considers usable/not usable at any given point in time.