Asset bundle downloads lagging after upgrading project from Unity 2018.X to Unity 2019.X

Hi, We have recently upgraded project from 2018.4.11f1 to 2019.4.21f1 We are downloading asset bundles on first launch on device using UnityWebRequest. With same code and same assets, the download completed within 1 minute with Unity 2018 builds but it takes way longer with 2019 builds, ~3-5 minutes on Android and ~2 minutes on iOS.

On iOS the logs didn't point out much, but on Android saw the following errors.

1:00:19.974: I/Unity(8020): (Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39) 03-17 21:00:20.394: E/Unity(8020): Curl error 51: Cert verify failed: UNITYTLS_X509VERIFY_FLAG_EXPIRED 03-17 21:00:20.394: E/Unity(8020):
03-17 21:00:20.394: E/Unity(8020): (Filename: ./Modules/UnityWebRequest/Implementations/TransportCurl.cpp Line: 813)

1:04:19.056: I/Unity(8020): (Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 39) 03-17 21:06:13.124: E/Unity(8020): Curl error 28: Connection timed out after 300000 milliseconds 03-17 21:06:13.124: E/Unity(8020):
03-17 21:06:13.124: E/Unity(8020): (Filename: ./Modules/UnityWebRequest/Implementations/TransportCurl.cpp Line: 813)

03-22 11:46:20.947: E/Unity(11092): Error while downloading Asset Bundle: Failed to decompress data for the AssetBundle 'http://awdafnkhs/bundle'. 03-22 11:46:20.947: E/Unity(11092): Curl error 23: Failed writing body (0 != 2856) 03-22 11:46:20.947: E/Unity(11092):
03-22 11:46:20.947: E/Unity(11092): (Filename: ./Modules/UnityWebRequest/Implementations/TransportCurl.cpp Line: 813)

03-22 12:27:47.581: E/Unity(2388): Curl error 52: Empty reply from server 03-22 12:27:47.581: E/Unity(2388):
03-22 12:27:47.581: E/Unity(2388): (Filename: ./Modules/UnityWebRequest/Implementations/TransportCurl.cpp Line: 813)

Has anyone faced similar Issue? If yes, were you able to fix it?