Sync issues. Problems with message synchronization between the application and the server

Good afternoon!
We use the free version of your product.
And there are problems with message synchronization between the application and the server.
Also, push messages come very long.
Therefore, we need your help to solve these problems.
Thanks in advance!

We use Rocket.Chat for a non-profit sustainability platform and our problem fits in well here.

Mistakes of several users with rather older smartphones.
“My operating system is Android 6.0.1 and the app version is 3.5.1. Several people in my engagement group have older phones and the same problem. Description: When you log in, all chats are updated. Then you can still see the chats and read the content, but you won’t receive new messages. In fact, the messages you read are still marked as read (both on the phone and when you log in to the browser on the laptop later), but you don’t receive new messages on the phone anymore. You have to log out and log in again in the app to receive new messages”.

When the app is reopened, it displays: “Your session is invalid. Pleas sign in again”. He also had to log in again to send new messages.

@michaelflohr Please check “Settings” menu and see which “Server version:” it is reporting for the problematic server you are connected to.

In addition, it may help if you add to the app and see if you encounter the same problem with our latest version of the server.