Spring OAuth2 - JWT token working on server but not on localhost?

I am seeing that myapp is able to process the OAuth2 JWT token properly on the server, but it is giving token conversion error on localhost.

My Flow is as below -

On Server, the myapp is behind our custom api-gateway

1. Getting Access Token - Through postman, I hit api-gateway token endpoint which in turn calls the authserver token endpoint. And I get OAuth JWT Token as response.

So, to summarize, postman
request: --(creds)--> api-gateway --(samecreds) --> auth-server
response: jwt token <-- (same jwt)-- api-gateway <--(jwt)-- auth-server

2. Next, I hit myapp endpoint - Again through postman, I hit api-gateway endpoints, which in turn hits the corresponding myapp endpoints. And I get the required response. For this request, before hitting the api-gateway, I set the header Authorization: Bearer JWT from step1

As the myapp developer, i know that the api-gateway is re-sending the JWT token to myapp using the same header mechanism i.e Authorization: Bearer JWT from step1. From the logs, i see this is the same value that I provided in postman when hitting the api-gateway

So, postman request: --(jwt)--> api-gateway --(same jwt)--> myapp
and response is some data, which is trivial for this discussion.

The decoded JWT Payload is as below:

{
  "app-userId": "c54a-4140-9fa0-0f39",
  "user_name": "abc@xyz.com",
  "scope": [
    "all"
  ],
  "exp": 1656929583,
  "authorities": [
    "app1_viewer",
    "app1_modifier",
    "app2_viewer",
    "app2_blog_creator],
  "client_id": "api-gw-client"
  ...
}

Plz note - "client_id": "api-gw-client" field in the above payload. So the auth-server is issuing the token to api-gateway client.

Now on mylocal dev env i.e myapp running on localhost - i am trying to achieve similar flow as on server.

On localhost, the myapp is NOT running behind api-gateway, but its hit directly

1. Getting Access Token - Through postman, I hit api-gateway (same server instance as in server flow above. i.e api-gateway/auth-server's are not running on localhost but are running on server) token endpoint which in turn calls the authserver token endpoint. And I get OAuth JWT Token as response.

So, postman request: --(creds)--> api-gateway --(samecreds) --> auth-server
response: jwt token <-- (same jwt)-- api-gateway <--(jwt)-- auth-server

Yes, this token can be used in Server Flow Step 2 and it works. And the decoded JWT token payload is same as I posted earlier i.e

{
  "app-userId": "c54a-4140-9fa0-0f39",
  "user_name": "abc@xyz.com",
  "scope": [
    "all"
  ],
  "exp": 1656929583,
  "authorities": [
    "app1_viewer",
    "app1_modifier",
    "app2_viewer",
    "app2_blog_creator],
  "client_id": "api-gw-client"
  ...
}

Plz note again - "client_id": "api-gw-client" field in the above payload. So the auth-server is issuing the token to api-gateway client. I am not sure yet if this field is trivial or important.

2. Next, I hit myapp localhost endpoint - Again through postman, But I hit myapp endpoints directly (not through api-gateway running on localhost). And for this request, before hitting, I set the header Authorization: Bearer JWT from step1.

BUT THIS TIME I GET ERROR:

p.a.OAuth2AuthenticationProcessingFilter : Authentication request failed: error="invalid_token", error_description="Cannot convert access token to JSON"

I want to know what is causing this error. I don't think the client_id: api-gw-client is causing this. Anyhow, I created a signed jwt token with client_id: myapp and used it in request. But still I get same error.
The key I am using on localhost matches(corresponds) to the one that the auth-server is using to sign. I double checked. So its for sure not a key issue.

I need the localhost based setup working, so i can test my api's locally with out deploying to server(deploying to server is quite time consuming in my case). So this setup is quite important for me to meet my deadlines. Any answers/suggests are greatly appreciated.

The Spring OAuth2 Libraries used in my project are as below -

1. org.springframework.security:spring-security-oauth2-jose:5.4.2
2. org.springframework.cloud:spring-cloud-starter-oauth2:2.1.3.RELEASE

And the class which is giving error is: OAuth2AuthenticationProcessingFilter.java (API Doc)