Admin page not working anymore

**The issue I am facing: My pi-hole admin page does not load anymore, i am getting "Can't reach this page"

webserver.log shows: pi@raspberrypi:~ $ sudo cat /var/log/pihole/webserver.log
[2025-03-11 07:23:32.508 CET 4759] Initializing HTTP server on ports "80,443os"
[2025-03-11 18:04:55.108 CET 4759] Authentication required, redirecting to /admin/login

My debug token is: 1kap1Xk5

Did you just upgrade to V6 and how are you attempting to reach the site?

Yes, some time ago but doesn't work since then, using http://ip/admin/

As it seems you have ssh access what is the output of sudo ss -tupln ?

the output is:
pi@raspberrypi:~ $ sudo ss -tupln
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
udp UNCONN 0 0 0.0.0.0:5353 0.0.0.0:* users:(("avahi-daemon",pid=266,fd=12))
udp UNCONN 0 0 0.0.0.0:53 0.0.0.0:* users:(("pihole-FTL",pid=486,fd=20))
udp UNCONN 0 0 0.0.0.0:68 0.0.0.0:* users:(("dhcpcd",pid=455,fd=10))
udp UNCONN 0 0 0.0.0.0:43092 0.0.0.0:* users:(("avahi-daemon",pid=266,fd=13))
udp UNCONN 0 0 192.168.1.161:123 0.0.0.0:* users:(("ntpd",pid=471,fd=18))
udp UNCONN 0 0 127.0.0.1:123 0.0.0.0:* users:(("ntpd",pid=471,fd=17))
udp UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("ntpd",pid=471,fd=16))
tcp LISTEN 0 0 0.0.0.0:443 0.0.0.0:* users:(("pihole-FTL",pid=486,fd=33))
tcp LISTEN 0 0 0.0.0.0:80 0.0.0.0:* users:(("pihole-FTL",pid=486,fd=32))
tcp LISTEN 0 0 0.0.0.0:53 0.0.0.0:* users:(("pihole-FTL",pid=486,fd=21))
tcp LISTEN 0 0 0.0.0.0:22 0.0.0.0:* users:(("sshd",pid=487,fd=3))

the funny thing now it is showing the login page, i enter my password and then it says 'connection reset'

I primarily wanted to make sure the webserver port was correct and it is. Not sure why the connection refused your now seeing.

One thing to try, can you clear you browsers cache / cookies and try again?

Your debug log shows Pi-hole's webserver to be configured and listening on ports 80/HTTP and 443/HTTPS.

Since you can access Pi-hole's UI only when using its IP, it is likely that your client or your browser is not using Pi-hole for DNS, so trying to resolve pi.hole would fail.

Run from the client that can't access Pi-hole's web UI, what's the output of:

nslookup pi.hole
nslookup flurry.com

How did the latter register in Pi-hole's Query Log?

I tried it on 2 computers which gave the same result.
So i took another laptop - opened chrome and there it works from the first try and fast...

Very strange - so only on that old laptop it is showing the page and able to logon.

Hi, the computer where it is working now does not have my pi hole as DNS server, but the page is working there, so i am able to access it on HTTP there.

Please share your nslookup results.

Sure:

Any client trying to access http://pi.hole/admin must use Pi-hole for DNS, as that is the only DNS server that knows how to resolve that name.

That Windows client isn't using Pi-hole for DNS, but an IPv6 link-local address.

Likely, your router is advertising its own IPv6 address as DNS server, allowing your clients to by-pass Pi-hole.

You'd have to find a way to configure your router to stop advertising its own IPv6 as DNS server, or to advertise your Pi-hole host machine's IPv6.

You'd have to consult your router's documentation sources on further details for its IPv6 configuration options.

If your router doesn't support configuring IPv6 DNS, you could consider disabling IPv6 altogether, provided you'd not depend on IPv6 for reasons.

If your router doesn't support that either, your IPv6-capable clients will always be able to bypass Pi-hole via IPv6.

This is likely due to the DHCP leases. The two that did work will likely work once you bounce
their network network ie on the windows machine your can run ipconfig /release followed by
ipconfig /renew.

It's an interesting issue in fact. The DHCP has to come from my provider modem unfortunately. For instance for my tv decoder it gives extra parameters, otherwise the tv won't work. I will investigate further.