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|rst) == syn 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|rst) == syn counter tcp option maxseg size set 90