Ipv6 port 80 no longer accessible

Hardware: Old laptop, HP EliteBook 8540w
YunoHost version:
I have access to my server : Through SSH | through the webadmin | direct access via keyboard / screen
Are you in a special context or did you perform some particular tweaking on your YunoHost instance ? : no

Description of my issue

Yesterday, my internet stopped working for a minute, modem didn’t show any connection to the ISP. I reset my modem, and all seemed fine, except for that my port forwards were deleted. I have UPnP enabled, so I reloaded the firewall to have them automatically added, and this is what the result was:

After running diagnostics, I came across this error:

[ERROR] Port 80 is not reachable from the outside in IPv6.

Full diagnostic report here

Upon testing if my server was really not reachable, the connection got timed out after 30 seconds. All other ports are working fine, only port 80 doesn’t work. So my server is still reachable through SSL, mail etc.

I’ve tried rebooting and reloading a bunch of times, besides the removal of the port forwarding nothing changed inside my modem. I’m not sure if this is something I need to solve with Yunohost configs or that I should give my ISP a call…