Pihole + VPN (without static IP option)

Hi,
I have VPN (expressvpn) configured on my router, the VPN provider does not offer IP static option, so when I'm trying to install pihole on my Raspberry, I have to options, whether automatically configure pihole, which gives me 10.0.0.x as my DNS address which of course does not work or configure it manually and enter a specific IP, which I don't know which one to add.
What should I do?
Any help would be appreciated.

The one that pihole receives

How can I check that?

10.0.0.12 to 10.0.0.255

I got 206.189.252.21
To which addresses should I change the DNS addresses in my DHCP section?

I changed it but it doesn't seem like my network going through the pihole

And for some reason it looks like I lost my internet connection on my raspberry (where pihole is installed)

Thanks.
For some reason it seems that I have internet connection through WiFi but I have this message : eth0: Link is down

OK, thanks to you I managed to set everything as it should be and even in ipconfig /all I see my pihole IP as the DNS and it's still does not working (I checked it with pihole's web page test from their website)

Just to check that I'm not doing a stupid mistake:
If I'm seeing under ipv4 on my pihole 10.0.0.10/20, what IPS should I put on my router dhcp DNS?

OK,
So I put 10.0.0.10 also as a secondary DNS?

I might up on something
When I'm hovering over the WiFi on my raspberry, I'm getting a different IP from the one in my pihole, for instance in my pihole the IP address is 10.0.0.12 and when I'm hovering over the WiFi it shows 10.0.0.16. I can login to pihole's admin interface through 10.0.0.16 and not the .12. It means that I need to configure on my routers 10.0.0.16?
If so, I think this IP is changing randomly, so I need to change my router DNS whenever the one on my raspberry changes?
BTW, really appreciate you patient and help. Thank you very much.

OK now the problem is like that,
When I'm setting my router DNS addresses to be as the on the pihole's, I'm losing my internet connection and I can't access to anything until I reboot the router (can't even do ipconfig/renew nor release), and the reboot changes pihole's IP, so it's kind of a loop.
Any thoughts?

How I can give pihole a static IP address if my VPN doesn't support it?

So if I understand correctly, I need to change my PC's (which PC? I have several) to 10.0.0.78, and then the dynamic IP of the raspberry to the same IP (how do I do that?)

I said as you said and the traffic of the specific PC went through pihole, but when I tried the same configuration on the router It didn't work.
What should I do?

Ok I probably made a mistake
I tried again to setup my PC with pihole and changed my PC DNS to pihole's DNS, but my PC DNS can't convert the domain name to IP.
I did as the following:
Connected my raspberry to my wifi

Configured pihole (once manually and once automatically)
Changed my PC DNS to pihole's (once the IP I've configured manually and once 10.0.0.2)
The gateway on my pihole is always the same.

Something that I noticed now is it doesn't matter if I configure pihole's IP manually or automatically, it always gets 10.0.0.2 as it's IP. I know it because I can access to pihole's admin interface only with this IP, albeit I see the IP I've configured manually on pihole's settings.

I think I'll settle to configure only one of my pcs with pihole and will give up for now for the router configuration.
Any thoughts how to continue?

Probably I didn't explain myself clearly
I don't have working PC with pihole, I was wrong when I said it's working.
Now when I set 10.0.0.2 as my PC DNS, it doesn't convert the domain name to ips. What should I do?

Yes, on my Raspberry everything work great, I have internet connection, DNS resolve is ok and every site accessed by my raspberry being recorded by pihole.

Yes, Raspberry works ok but when I change my laptop's DNS to 10.0.0.2, my DNS doesn't resolve domainames.

Ok, I just got what you meant
On the raspberry I get response only for
nslookup pi-hole.net 127.0.0.1
for
nslookup pi-hole.net 10.0.0.2
I get
";; connection timed out; no servers could be reached"
On my PC, for 127.0.0.1 I get
"*** unKnown can't find pi-hole.net: no response from the server"
For 10.0.0.2 I get 4 times
"DNS request timed out.
timeout was 2 seconds."
*** Request to unKnown timed out

(I tried the nslookup on my PC once with regular DNS and once with 10.0.0.2 as my DNS)

BTW, my IP on pihole has been changed, but still I can get to the admin interface only with 10.0.0.2.

; connection timed out; no servers could be reached”
:frowning:

Thank you very much for your efforts. I really appreciate your efforts.