What server_ip to use?

[albertofustinoni]

Asking here since the documentation is unclear: what is the server_ip parameter in the network section of the config?
Can multiple ones be specified, or is it supposed to be a single master node?

I have two dumb access points in my network (gateway/DHCP/DNS is an OPNSense box), on IP 10.0.0.21 and 10.0.0.22.

If I configure both as:

option network_option '3'
option server_ip '10.0.0.21'

Only the 10.0.0.22 AP sees radios and devices for the whole network, while 10.0.0.22 only sees his local ones.
Is it expected behavior for the server to send nothing back to the other nodes?

Since I only have two nodes, I can get around this by setting the other node's IP as the server (so AP at 10.0.0.21 gets 10.0.0.22 as the server and vice versa) - but is this how DAWN is meant to be configured? And if so, why is the server parameter a single IP address instead of a list?