How to resolve Unbound causing N/A Reply for certain domains?

Note that Unbound is a DNS service, it doesn’t look up URLs, it looks up domain names.

I don't see how stating the obvious is helpful.

I've set up Unbound as a recursive DNS server, but that doesn't do anything to the fact that I can access these sites when I bypass Unbound by setting another DNS (from my ISP for instance). That makes me think it's not Pi-Hole or something else, but Unbound (a faulty setting of mine? or a problem at the other side?) causing the problem. I can see in the query logs they are getting N/A as reply.

And yet, another user with similar set up could reach these sites. I already reinstalled and followed all the steps and still the same problem with those... domains.

Just read a message on Reddit. Similar problem was solved by unchecking 'Block UDP flood' in the router. Can't find this setting in my TP Link Archer AX55, but makes me think the router could be the culprit. (?)

Remember you posted URLs, not simple domain names.

You're right and that was an error, but the topic clearly says _domains_. Again, this doesn't help my in any way.

This one is definitely in need of plonking.

That problem seems to be solved. I forgot to mention I was (am) working behind a double NAT. My ISP's modem (crippled; very few options) and my own router (more options). Yesterday, I tested a fresh install (Bookworm, Pi-Hole & Unbound) on an RPi4 on a network with the same modem (same ISP), but directly connected to the modem. Those domains could be reached without a problem.

I now have some options :switching my ISP's modem with a Fritz!Box or switching the modem with another one my ISP offers, one that can be used in Bridge Mode. Unfortunately, I just found out my router (TP-Link Archer AX55) that I just bought doesn't support Bridge Mode. So I would have to buy a new router, an AP with at least one extra Ethernet port and a 30 m cable.

I decided to give this a pass and have chosen Cloudflare (DNSSEC) to be Pi-Hole's DNS. Too bad about Unbound... (My ISP blocks port 53, so portforwarding wasn't an option either.)