Works for IPv6, unable to test with double NAT v4.

?
You Means, custom port like 1024-65535 are blocked?
I tested on your provided website, nope, it don't support IPv6, showing invalid.

https://www.port.tools/
This one tested for IPv6, port 16823 or 49888 works, but sadly unable to showing filtered or closed lol.
Any reason you wanna open on those common port, except getting DDOS testing on your network???

Well, as I say, me 30M users, so private IPv4, only can test for IPv6 lol.
Did you think about the possible of firewall?

And, did your qbittorrent running on port 21, 80 or 49888?
You know, port forward, for utorrent or custom gaming server or NAS file hosting or xxx, need be to running as a server on the computer that you forwarded, and also, most software support UPnP port forward, so no need manual port forward.
Doing port scan without a server open on that port, sure is no respond la.

Guess public IPv4 not gonna be useful as it is blocked for custom port lol.
Maybe you think about just build a small server for all of you IoT?

So no need care about port forward, as long as they still open you up for port 80 88
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Wait, your screenshot is showing port 80 closed, did you really open any iot on port 80?
Or, you are getting switch to Private IPv4???

are you on CGNAT or not?
perhaps you did not open up your firewall to allow those on device?

if you're opening UDP port it wont show on those port scanner. only TCP.