ServerDisconnected due to error: Timeout

Hello. I am working on a MMO game using UNet. I have a headless server running on Linux Ubuntu hosted on AWS. Clients get connected to it and players can play with each other. After about 15 to 20 minutes all clients are disconnected and server shows the following error:

As I am new to multiplayer I am unable to figure out what causes it. I am seeing the resources on AWS and everything looks fine.

Following are my timeout settings in NetworkManager:

Minimum Update Timeout: 1 ms

Connect Timeout: 5000 ms

Disconnect Timeout: 5000 ms

Ping Timeout: 3000 ms

Any help would be greatly appreciated.