Hi,

I am wondering why I cannot select /24 for my docker containers.

I have a class C network 192.168.42.0/24 for the unraid server itself on eth0. Then I have added two IPv4 only VLANs 10 and 20 with no address assignment for unraid. Docker is set to macvlan with host access to custom networks Disabled. Under IPv4 custom network on interface br0.10 (i.e. for VLAN 10) I can now enter a subnet (here 192.168.10.0) but I can only select /25 from the dropdown. Same for br0.20.

Anybody know where this comes from? I'd like to allocate the containers a higher IP address than 127, thus the subnet mask must be /24. Also I am not sure how this might affect other parts of networking which is completely on /24...

Best,

Klayman

Update to 7.1.4, it has a fix for that.

Thanks, that did the trick. Is it also possible that the containers request their IP from an external DHCP?

I don't think that is possible.

On 6/19/2025 at 9:20 AM, Klayman said:

Thanks, that did the trick. Is it also possible that the containers request their IP from an external DHCP?

only if the docker netoekr is setup with a aux dhcp ip range ... so it will get a ip within this set of the specfied ip range...
https://docs.docker.com/engine/network/

Not possble for default br0 netowrk created vai the web Ui...

Unraid is not netowrking equipment...

Let’s say you want to:

• Create a macvlan Docker network on VLAN 10 (br0.10)

• Use subnet 192.168.10.0/24

• Reserve container IPs from 192.168.10.128 to 192.168.10.250

• Set the gateway to 192.168.10.1 (or adjust to match your infra)

• Interface is br0.10 (Unraid's VLAN 10 bridge)

• Parent interface is eth0.10

create your own docker network this will give a dhcp ip to a docker in that network 192.168.10.x based on the 128/25 subnet

docker network create -d macvlan \

--subnet=192.168.10.0/24 \

--ip-range=192.168.10.128/25 \

--gateway=192.168.10.1 \

-o parent=br0.10 \

vlan10_net

*You can do the same for VLAN 20 (e.g., br0.20 and 192.168.20.0/24).

Explanation:

• --subnet: The entire subnet available for Docker on that VLAN.

• --ip-range: Limits the IPs Docker will actually assign (you can make this smaller or control ranges to avoid overlap with statically assigned IPs).

• --gateway: Your network gateway for the VLAN.

• -o parent=br0.10: The physical VLAN interface; Unraid’s GUI creates br0.x for VLANs.

docker network ls

docker network inspect vlan10_net