The status of the interfaces for a network switch shows as “unknown” in SolarWinds’ platform...

Comprehensive and Detailed Explanation From Exact Extract:

If a node is up but its interfaces show as “unknown,” this usually means the interfaces are not currently being managed/monitored in the SolarWinds platform.

From the documentation:

“If interfaces are not selected for management during discovery or have been removed from monitoring, their status appears as ‘unknown’ even though the parent node is up.”