I used the search term “macvlan” in the forum search and had this thread as first hit:
The section “Syntax to create sub interface:” describes how to add a macvlan client interface to your host. It shows an example of the commands needed to workaround the macvlan limitation I was refering to earlier.
Is 192.168.3.0/24 your local lan?!? If so, this is a call for trouble, as you did not define the --ip-range parameter when creating the macvlan, which should be a range within your subnet that is outside a dhcp servers reach. Your whole setup just works reliable so far, because you declare fix ip addresses to your containers.
Good luck!