Enable to setup an overlay network

I’m brand new to the Docker world and a trying to setup a test environment on my VMware Worktation.
I’ve deployed two Docker Hosts on two separate subnets.
These are interconnected through a router running on Windows Server.
I’ve created a swarm with these two hosts/nodes.

So far so good.
They can communicate and so on.

Now I’d like to create an overlay network between both.
I’ve created this overlay network on the swarm manager.

I’ve deployed a new service with a replicas=2, but the two instances are created only on my swarm manager.

When looking at the “docker service ps name-of-my-service --no-trunc”, I get this error message

error creating external connectivity network: Failed to Setup IP tables: Unable to enable SKIP DNAT rule: (iptables failed: iptables --wait -t nat -I DOCKER -i docker_gwbridge -j RETURN: iptables: No chain/target/match by that name.

Any help with this would be really appreciated.