RHEL: vlan devices show drops on the qdisc and some TCP connections are slow

Issue

• Some TCP connections to a Windows machine showed large multi-second delays. This is a TPROXY configuration and there is a ingress and egress connection.
• What we observed is that on one of these connections RHEL had a congestion window of only 1. Therefore it waited for the Windows side to ack before sending another packet. The Windows side went into delayed ACK mode for 200ms further slowing the connection down.