There is a possibility your IP was blocked. While using the SIM with the problem, go to Google and search what is my IP, note that. Then from the other connection, open a ticket with support, and provide the information from your post and the IP.
https://support.chess.com/customer/portal/emails/new
Hi I have one plus 6t mobile with dual sim - 1. Jio (4G) 2. Vodafone. Jio is primary sim with mobile data enabled. From last few days, my chess.com app is not able to connect using Jio sim. Also i am not able to access chess.com site in browser with Jio sim. However everything works when I switch mobile data to Vodafone sim. But the issue does not seem related to Jio network because i am able to access internet (except chess.com) using Jio and it is very fast. What could be the issue? I dont want to use Vodafone because its very slow. Thanks Rahul OS Version: Android API 28 Device: ONEPLUS A6010 App Version: 19703|3.8.4