3204327 - Write operation failed - slow network connection

In SAP BTP application a timeout happens accessing the on-premise system via SAP Cloud Connector.

The application log contains a similar entry:

java.util.concurrent.TimeoutException: Request timeout to localhost/127.0.0.1:20003 after 60000 ms

The Cloud Connector log file, ljs_trace.log contains such WARNING and ERROR entries:

#WARN#com.sap.core.connectivity.spi.processing.OutboundConnectionReader#tunnel-client-15-4#0x9b9f7bce#Threshold of 15,000 passed. Message of type 3 (payload) with payload size 8,962 sent for 15,457 milliseconds over tunnel channel [id: 0x01e0f0e6, L:/<scc IP> - R:connectivitytunnel.us3.hana.ondemand.com/169.145.118.141:443]. Tunnel id "account:///<subaccount>"

#ERROR#com.sap.core.connectivity.spi.processing.OutboundConnectionReader#tunnel-client-15-4#0x9b9f7bce#Write operation FAILED for message of type 3 (payload) with payload size 16,149 for tunnel channel [id: 0x01e0f0e6, L:/<scc IP> ! R:connectivitytunnel.us3.hana.ondemand.com/169.145.118.141:443]. Cause: "io.netty.channel.StacklessClosedChannelException". Tunnel id "account:///<subaccount>"
#ERROR#com.sap.core.connectivity.spi.processing.OutboundConnectionReader#tunnel-client-15-4#0x9b9f7bce#Write operation FAILED for message of type 3 (payload) with payload size 16,149 for tunnel channel [id: 0x01e0f0e6, L:/<scc IP> ! R:connectivitytunnel.us3.hana.ondemand.com/169.145.118.141:443]. Cause: "io.netty.channel.StacklessClosedChannelException". Tunnel id "account:///<subaccount>"
#ERROR#com.sap.core.connectivity.protocol.http.handlers.HttpRequestStateHandler#tunnel-client-15-4#0x9b9f7bce#Unexpected HTTP error:
com.sap.core.connectivity.protocol.http.handlers.HttpProtocolException: null
 at com.sap.core.connectivity.protocol.http.handlers.HttpProtocolClientCodec.exceptionCaught(HttpProtocolClientCodec.java:83)
 at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)

...

Caused by: com.sap.core.connectivity.spi.TunnelWriteException: null
 ... 46 common frames omitted
Caused by: io.netty.channel.StacklessClosedChannelException: null
 at io.netty.channel.AbstractChannel.close(ChannelPromise)(Unknown Source)

SAP BTP

SAP Cloud Connector

KBA , BC-NEO-CON , Neo to On-premise Connectivity service , BC-MID-SCC , SAP Cloud Connector On-Demand/On-Premise Connectivity , How To