Please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:
HTTP/1.1 200 OK
...
X-Pi-hole: The Pi-hole Web interface is working!
...
Server: lighttpd/1.4.59
If you get that then the Pi-hole web interface is working and the problem is your web browser, perhaps an extension or VPN or private browsing option which is interfering with your access.
Ping is ok. My nextcloud is working well. I already made work nextcloudpi + pihole before on another raspberry. And I don't get why I can't acces the web interface. I know Nextcloud interface is on the port 80, so I have to set another port for the pihole, but for some reason, I can't reach it
Note about your results:
You used port 8888 on the first command, but port 8080 on the second one...
This doesn't look like what I expected (maybe it's a typo?).
Did you use the same port on both commands?
If both commands used the same and correct port, they received the expected headers from lighttpd. This means the web interface can be accessed from your RP4. Looks like the issue is on your network.
Yeah, just don't worry about the port. I'm back on port 8080 in lighttpd.conf. To avoid confusion with you, I replace 8080 by 8888 on forum. But I forget to replace it on the second command. At final, it becomes more confused :s
Both command worked on port 8080.
So the problem comes from my network ?
Currently, I use two RP4, one for nextcloudpi (192.168.1.32), where I'm trying to install pihole. And a second one on RaspiOS (192.168.1.19) where I have a pihole fully functional, web interface is ok and work on port 8080.
I can access the web interface from 192.168.1.19:8080/admin.
The thing is I want to merge nextcloudpi and the pihole, in order to free the second RP4.
So I want my pihole functional on nextcloudpi.
About my nextcloudpi, it is configured with a name domain, in order to access to my nextcloud when I'm not at home. It could come from this configuration ? Maybe Nextcloudpi doesn't allow connection from other port than 443 ?
I can't answer with 100% accuracy because I don't use Netxcloud and I don't know your apache config, but I doubt this domain name will interfere when you access the web site via IP.
I don't know why the web interface is accessible from you RP4, but not from other devices on the same network (you said there are no firewalls).
Is there any active firewall rules on your router?