I need serious help with bungeecord!

03.04 17:50:41 [Server] WARNING -> UpstreamBridge - read timed out 03.04 17:50:41
[Server] INFO disconnected with: ReadTimeoutException : null 03.04 17:50:41
[Server] INFO -> UpstreamBridge has disconnected

all my server connection throttles are set to -1 already and in offline mode except the bungeecord server which is online. my staff and i have no idea whats going on. please help

all our servers are 1.15.2