You shouldn't enable Mesh unless you need the Mesh functionality. This is where you connect APs to the network wirelessly, rather than by an Ethernet cable back to a switch that is connected to the main network.
There are no issues mixing Wi-Fi 5 and Wi-Fi 6 access points. Wi-Fi 6 is backward compatible with all previous Wi-Fi standards. Unleashed can manage Wi-Fi 5 and 6 Access Points on the same system. Just as you're currently managing 802.11ac Wave 1 (R500) and Wave 2 (R710) on the same system today.
However you will need to upgrade your Unleashed network to a newer version to support the R750 APs models. Unleashed version 200.8 is the first release to support R750 and unfortunately this does not support R500. So you will need to replace all the legacy R500 APs with a newer model.
Darren, if you're still seeing these ... I have a R750 that is currently running Unleashed Version 184.108.40.206.319. I have a ton of R500's that I'd like to use to supplement the R750 and get a bit more coverage. I'm not worried about top end speeds in those situations ... and the number of clients is less than 25, and I'm not pushing bandwidth.
As I'm understanding this thread, for the R500's to think of the R750 as the master, it would have to be on version 200.8 or higher. But, R500's are EOL and only go to 200.7. In my case, I believe that 220.127.116.11.127 is the highest that I could find and what I have running ... but the R500 doesn't see the R750.
Two things: First, would really appreciate it if Ruckus would release the 200.8 version for R500. After all, those early adopters of Wave 1 shouldn't be penalized. Even if you can do a full 200.8+ for R500, maybe just a patch that allows it to recognize the R750 (and other current versions) if it's not overly burdensome.
Second, am I understanding from what you are saying that I can get the R500 to work if I pull them off ethernet, and let them instead mesh to the R750? Will the R750 still act as master?
Any other suggestions welcome (other than replacing all the R500s, that is).