Which switches and access points does Passbeam support?

Any make that supports RADIUS or RADSec. Passbeam is a standards-based RADIUS server, so there's no compatibility list to be on.

That includes Cisco Catalyst, HPE Aruba, Arista, Juniper, Cisco Meraki, Extreme, Ruckus, Fortinet and Ubiquiti UniFi, and older equipment from the same makers. VPN gateways work too, such as pfSense, OPNsense, FortiGate or a Windows RAS server, as long as they can pass EAP-TLS through to RADIUS. A gateway that can only send a username and password won't work.

What matters is which transport your equipment supports. Use RADSec where you can. Cisco Catalyst 9000, ArubaOS-CX, Junos and Arista EOS support it on wired ports, and so do most current access points. Standard RADIUS is fully supported too, and it's what UniFi switches, Meraki MS switches and VPN gateways use. A site can use both at once. See “RADIUS or RADSec: which should I use?”.

Your site's Connect tab has the menu path or CLI commands for Cisco, HP / Aruba, Arista, Juniper, Meraki and UniFi, and the values for anything else. Meraki also has its own guide with screenshots: “How do I set up Cisco Meraki with Passbeam?”.

If a port authenticates nobody, check the switch's own RADIUS statistics first. If its Access-Request counter is zero, the switch never sent anything, so the certificate and shared secret aren't the problem.