iptables-translate -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu nft add rule ip filter FORWARD tcp flags syn / syn,rst counter tcp option maxseg size set rt mtu iptables-translate -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 90 nft add rule ip filter FORWARD tcp flags syn / syn,rst counter tcp option maxseg size set 90