PUBNUB operations throws PNTimeoutCategory often

I am using pubnub server in my chat app. It works fine but often I am getting PNTimeoutCategory error while doing pubnub operations like subscribe, unsubscribe, publish etc. How to handle this?

 pubnub = new PubNub({     authKey: auth_key,     publishKey: publish_key,     subscribeKey: subscribe_key,     ssl: true,     uuid: provider_id,     logVerbosity: __DEV__, });

and I subscribe channels like below:

pubnub.unsubscribe({    channels});