unstable bridge with debian 10 server

[Sorry for the clerical errors, I’m French]

I would like to use KVM on my debian server.
So I install the packages and i create the bridge (br0) :

 This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug enp8s0 #my main connection
iface enp8s0 inet static
# This is an autoconfigured IPv6 interface
iface enp8s0 inet6 static
        address 2a01:cb06:d2:6c00:1ac0:4dff:fe60:bf74
        gateway 2a01:cb06:d2:6c00::/56

iface br0 inet static #my bridge
        bridge_ports enp8s0
        bridge_stp off
        bridge_waitport 0
        bridge_fd 0

When I run

ifup br0

, i don’t have problem to start

Waiting for a max of 0 seconds for enp8s0 to become available.

Waiting for br0 to get ready (MAXWAIT is 2 seconds).

When I run

ifup br0

, I have no problem to start with.

But there are problems of stability.
Firstly, the server has 3 IP addresses: (enp8s0), and
Another thing, I installed “pi hole” (a dns) and when I wrote the 3 IP addresses, I arrived all the time on the main interface of “pi hole”. I don’t know if this is normal or not.

And sometimes the whole connection of my server stops for no apparent reason.
→ VNC and SSH are stopped and it is not possible to connect to the “pi hole”.

So when I go to my server offline and try to restart the connection.

The only solution is to restart the server.

Do you have a solution to have a stable connection with a KVM bridge.
Thank you in advance.

For information: My server → Debian GNU/Linux 10 server (buster) / ryzen 3 / 8go ram / connected with an internet cable to my orange livebox.