Ios sendbird chat reconnect session error and register push throws error code Code=800220

For ios app, sendbrid chat connect method being passed user id and access token (rather than session token). Sendbrid makes a connection. Then this message is printed on xcode console after sometime:

SendbirdChat [Session] [ERROR] reconnect(sessionKey:) Cannot perform reconnect because session key is missing

After trying to register device push token, it throws an error and printed the error to debug. This error below. Any suggestions.

Sendbird Push registration error: Optional(Error Domain=core Code=800220 “Request couldn’t be generated properly.” UserInfo={NSLocalizedDescription=Request couldn’t be generated properly.})

// If problem, please fill out the below. If question, please delete.
[SDK Version]
// What version of the SDK are you using?
iOS SendbirdChatSDK 4.2.3

[Reproduction Steps]
// Please provide reproduction steps and, if possible, code snippets.

// How frequently is this issue occurring?

[Current impact]
// How is this currently impacting your implementation?

Now trying to connect with just SENDBIRD USERID without the access token like so:

SendbirdChat.connect(userId: SENDBIRD_USERID)

Still throwing the session key reconnect error.

[Session] [ERROR] reconnect(sessionKey:) Cannot perform reconnect because session key is missing

On http request header I see Connection: keep-alive, but in the result is KEPT ALIVE is NO

Is there something need to be done to handle reconnect and preseve the session? ConnectionDelegate?

On iOS I don’t see the websocket connection started. Running iOS 15. Sendbird Chat SDK is being used on the iOS is SendbirdChatSDK 4.2.3. In Android Sendbird starts the websocket connection. I am guessing websocket should be started in iOS as well.

Seems like bug on iOS15. Can someone tell me what is the websocket data frame payload size from Sendbird Server? 8KB+?