net.ipv4.tcp_tw_recycle causes problems with NAT-ed clients.

tcp_tw_recycle (Boolean; default: disabled; since Linux 2.4) Enable fast recycling of TIME_WAIT sockets. Enabling this option is not recommended since this causes problems when working with NAT (Network Address Translation).

net.ipv4.tcp_tw_reuse seems fine to use, but literature about its real effects is sparse.

This link http://vincent.bernat.im/en/blog/2014-tcp-time-wait-state-li... mentions both of them.