This worked for me when I added port 3306, while it was only 1433, it did not work.
therefore, a security group was created in this way
security group vpc-XXXXXX
MY SQL / TCP / 1433 / 0.0.0.0 / 0
MY SQL / TCP / 1433 / :: / 0
MTSQL / Aurora / TCP / 3306 / 0.0.0.0 / 0
MSSQL / Autora / TCP / 3306 / :: / 0
after TYPE / Protocol / Port Range / Source headers
source share