iptables-translate -A INPUT -p icmp -m length --length 86:0xffff -j DROP
nft 'add rule ip filter INPUT ip protocol icmp meta length 86-65535 counter drop'

iptables-translate -A INPUT -p udp -m length --length :400
nft 'add rule ip filter INPUT ip protocol udp meta length 0-400 counter'

iptables-translate -A INPUT -p udp -m length --length 40
nft 'add rule ip filter INPUT ip protocol udp meta length 40 counter'

iptables-translate -A INPUT -p udp -m length ! --length 40
nft 'add rule ip filter INPUT ip protocol udp meta length != 40 counter'