OAuth Issue with Magento 2 Integration with Royal Mail Click and Drop

[traknet]

Hi, Royal Mail Click and Drop is getting an error when trying to connect to my Magento 2.3.5 Integration. Error is:

"Magento Invalid Magento Identity Confirmation, "oauth_consumer_key" is required. Enter and try again, "oauth_signature" is required. Enter and try again, "oauth_signature_method" is required. Enter and try again, "oauth_nonce" is required. Enter and try again, "oauth_timestamp" is required."

I've put the callback and identity strings into the integration correctly and granted all permissions to the integration,

My questions are:

1. Should Magento 2.3.5 out of the box have OAuth ready to use? The OAuth settings in Admin are the default ones and look ok.

2. Is there anything you need on the server to allow OAuth to work?

Any advice will be appreciated.

Regards

Janak

[traknet]

I've had OAuth installed on the server but this has made no difference - the same error is being reported by Click and Drop.

Any ideas anyone?

[traknet]

I evetually got this working. I installed and enabled PHP-FPM.

I wasted a lot of time on this so this may help someone if they have problems with integrations.