wordpress-serverless with s3-upload plugin

I have build a serverless architecture for wordpress using serverless components such as lambda,cloudfront,apigateway and s3. As lambda is Read-only file system we can't store media files so I tried to use s3. For Integrating s3 with wordpress, used S3-uploads plugin (https://github.com/keichan34/wordpress-on-lambda/tree/master/src/php/wp-content/plugins/S3-Uploads-2.1.0) but It shows Endpoint Requested Timed out (or) The server cannot process the image. This can happen if the server is busy or does not enough resources to complete the task as shown in below screenshots

So tried by providing permission open to all but also shows same issue and also configured reserved concurrency results same issue. While recording Cloudfront logs, the specfic request shows error logs as

2023-10-17	12:33:51	MAA51-P3	418	117.249.156.215	POST	d2v41wfs0fn3av.cloudfront.net	/index.php	504	https://d2v41wfs0fn3av.cloudfront.net/wp-admin/post-new.php	   Mozilla/5.0%20(Windows%20NT%2010.0;%20Win64;%20x64)%20AppleWebKit/537.36%20(KHTML,%20like%20Gecko)%20Chrome/117.0.0.0%20Safari/537.36	rest_route=%252Fwp%252Fv2%252Fmedia&_locale=user	wordpress_test_cookie=WP%2520Cookie%2520check;%20wordpress_logged_in_1bc330ff7d3c3261e08332c607093121=user%257C1698735401%257CtY3GY9TqICLaSeCRltftD4dieM50MoSiBYGQILC9VeV%257C9f39b627c78a235d006e97408e3c473868f840dc0c39a4304602280c4b99f0bb;%20wp-settings-time-1=1697545970	Error	ftxhaD2Ig5rtQxdG9mpreZom4e_zPYh9BQfJBKzmsCn1O5npsX_njA==	d2v41wfs0fn3av.cloudfront.net	https	1448	29.920	-	TLSv1.3	TLS_AES_128_GCM_SHA256	Error	HTTP/2.0	-	-	61330	29.920	OriginError	application/json	41	-	-


2023-10-17	12:30:54	MAA51-P3	420	117.249.156.215	POST	d2v41wfs0fn3av.cloudfront.net	/wp-admin/async-upload.php	504	https://d2v41wfs0fn3av.cloudfront.net/wp-admin/media-new.php	Mozilla/5.0%20(Windows%20NT%2010.0;%20Win64;%20x64)%20AppleWebKit/537.36%20(KHTML,%20like%20Gecko)%20Chrome/117.0.0.0%20Safari/537.36	-	wordpress_sec_1bc330ff7d3c3261e08332c607093121=user%257C1698735401%257CtY3GY9TqICLaSeCRltftD4dieM50MoSiBYGQILC9VeV%257Cc43e2d879b5974e4dd1cf84f6d7749ec2f3280264efc98ffcc5f488b6adae9f8;%20wordpress_test_cookie=WP%2520Cookie%2520check;%20wordpress_logged_in_1bc330ff7d3c3261e08332c607093121=user%257C1698735401%257CtY3GY9TqICLaSeCRltftD4dieM50MoSiBYGQILC9VeV%257C9f39b627c78a235d006e97408e3c473868f840dc0c39a4304602280c4b99f0bb;%20wp-settings-time-1=1697545797	Error	2vOcQkfWLTwBX11pRDwdXL1HPyJetzrjvP7c6qYPOwH-JAzizOoiXg==	d2v41wfs0fn3av.cloudfront.net	https	2092	29.921	-	TLSv1.3	TLS_AES_128_GCM_SHA256	Error	HTTP/2.0	-	-	61330	29.921	OriginError	application/json	41	-	-

In apigateway x-ray traces it also same 504 error so I don't able to find the issue. Help me to resolve this case if you have already gone through this issue or suggest any clarification on this case.

Thanks in advance.