Welcome to Microsoft Q&A platform and thanks for using Azure services.
As I understand from the question, you are getting error when connecting to Redis cluster in US East using ioredis library of node js project.
I checked through Azure portal that the Region looks fine.
I would recommend you to look into the below links and the solutions provided which might help in your case:
ioredis - ClusterAllFailedError: Failed to refresh slots cache
ClusterAllFailedError: Failed to refresh slots cache.
ClusterAllFailedError: Failed to refresh slots cache. with Cluster mode and TLS enabled
Please let us know if this helped. If not, do let us know of further queries.
Thank you!