As of version 4.10, R Remote is required to update Rio firmware. Typical configurations (including Auto IP and Static IP (Auto) do not work.
I discovered that with the proper IP addresses assigned by a DHCP server, R Remote works with Mac OS.
With a Class-C IP address (subnet mask 255.255.255.0), Rio IP addresses above x.x.x.128 work while those below that do not.
I set the Rio DIP switches for DHCP (2 down, 3 up for Rios -- Tios are different). This may not be necessary but I wanted to avoid Auto IP addresses.
Then, set the DHCP server to provide addresses of x.x.x.128 and above.
A reboot of the Rios was necessary for the new IP addresses to be assigned.
I do not know how different subnet mask settings affect the range of IPs that work.
I tried Auto IP, static IP (auto) without success.
I suspect that after R Remote connects, you could manually set an IP address in the range that works.
Rios use three separate IP addresses: one for Dante Primary, one for Dante Secondary (redundant mode) and one for control (used by R Remote). Control IP configuration is through R Remote so you can't set it unless R Remote connects. Dante Primary and Secondary IP config.
Some routers (like my Asus) show IP and MAC addresses for all connections so this may provide an additional troubleshooting tool.