Access KVM VM over the network from a Docker container

KVM is used to host some VMs in the network 192.168.2.1/24. Docker is running on the same machine in 192.168.3.1/24. I need to configure networking so that Docker containers can access a KVM VM. For testing purpose I have two machines, each running a webserver to test working connections using wget:

Docker Container on 192.168.3.2

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  • KVM VM on 192.168.2.2

    In KVM I configured a virtual network as redirection to all physical networks. This allows me to access the Docker container from A KVM VM. But not working is the other way round: Accessing the KVM VM (192.168.2.2) from the Docker container (192.168.3.2).

    docker network create --driver=bridge --subnet=192.168.3.1/24 my-network
    

    The container is started like this:

    docker run --name=gogs --network=my-network --ip=192.168.3.2 -v /var/gogs:/data gogs/gogs
    

    What is the KVM virtual network wizard doing here that Docker is missing?

    net.ipv4.ip_forward=1 is enabled in /etc/sysctl.conf and I did a reload using sysctl --system.

    Docker network interface

    br-7b4175d9379d: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 192.168.3.1  netmask 255.255.255.0  broadcast 0.0.0.0
        inet6 fe80::42:9ff:fe6b:75dd  prefixlen 64  scopeid 0x20<link>
        ether 02:42:09:6b:75:dd  txqueuelen 0  (Ethernet)
        RX packets 90  bytes 41977 (41.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 116  bytes 18172 (18.1 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    

    KVM network interface

    virbr0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 192.168.2.1  netmask 255.255.255.0  broadcast 192.168.2.255
            ether 52:54:00:85:7f:95  txqueuelen 1000  (Ethernet)
            RX packets 1463  bytes 101054 (101.0 KB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 1214  bytes 1490407 (1.4 MB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    

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