fix: configure S3 client with explicit endpoint URL and v4 signature version

api/views.py

@@ -287,11 +287,14 @@ class PresignedUrlView(APIView):
         if aws_access and aws_secret:
             try:
                 import boto3
+                from botocore.client import Config
                 s3_client = boto3.client(
                     's3',
                     aws_access_key_id=aws_access,
                     aws_secret_access_key=aws_secret,
-                    region_name=region_name
+                    region_name=region_name,
+                    endpoint_url=f"https://s3.{region_name}.amazonaws.com",
+                    config=Config(signature_version='s3v4')
                 )
                 presigned_url = s3_client.generate_presigned_url(
                     'put_object',