Opening ports for torrent

[mat999io]

I'm root and I use Torrent apps like LibreTorrent (free) or Flud (paid). I'm usually behind a thirdparty firewall so In older Android versions I could set 443 as incoming port. This does not work in recent Android versions (I can't download). Questions:

1. Are all ports below 1024 blocked by default for incoming connections?
2. Could an afwall custom script (iptables rule) solve it?
3. Does the app need to be run as root?
4. Incoming port suggestions? 8443 and 8080 do not work.

I have a custom script to allow Cloudflare Secre DNS DoT (tls://one.one.one.one or tls://1dot1dot1dot1.cloudflare-dns.com) and it works fine: "iptables -I afwall -p tcp --dport 853 -d 1.1.1.1,1.0.0.1 -m owner --uid-owner root -j ACCEPT"

If the torrent app is com.delphicoder.flud.paid with UID 10324, what iptables rule could work?

Thanks.