iptables-translate -t filter -A INPUT -p tcp -m multiport --dports 80,81 -j ACCEPT
nft add rule ip filter INPUT ip protocol tcp tcp dport { 80,81} counter accept

iptables-translate -t filter -A INPUT -p tcp -m multiport --dports 80:88 -j ACCEPT
nft add rule ip filter INPUT ip protocol tcp tcp dport 80-88 counter accept

iptables-translate -t filter -A INPUT -p tcp -m multiport ! --dports 80:88 -j ACCEPT
nft add rule ip filter INPUT ip protocol tcp tcp dport != 80-88 counter accept

iptables-translate -t filter -A INPUT -p tcp -m multiport --sports 50 -j ACCEPT
nft add rule ip filter INPUT ip protocol tcp tcp sport 50 counter accept