Can't connect to aws mysql rds from mysql workbench for some region

I created aws mysql rds for different region with public access configuration from my free tier account.

Following were the regions:

• N. virginia
• Singapore
• Mumbai

For the above regions, I can connect only to N. virginia region rds from my local mysql workbench. But for other two regions, I am not being able connect to the workbench.

Is there any limitation for other regions? can anyone kindly answer?

TIA