Connections stall, fail, or take a long time to complete due to excessive TCP retransmissions

Issue

• When using iptables, a lot of retransmissions are performed, the connection is reset.
• When using firewalld, connections are stalled (hung) for long periods of time and may be reset.
• TCP packets/segments containing select acknowledgement (SACK) options are ignored when iptables is being used
• System is not sending TCP Fast Retransmissions/Retransmits after receiving three Duplicate Acknowledgements when iptables is used
• SCP transfers are intermittently failing
• TCP transfer stalls and eventually disconnects with "broken pipe" (EPIPE) message
• In Wireshark/tshark, SACK Left Edge (SRE) and SACK Right Edge (SRE) on Dup-ACK packets are much larger than the relative SEQ and ACK numbers