UPC and APC are fiber connector types. UPC (Ultra Physical Contact) connectors have a fiber connector end face that has been polished to a dome-shape. APC (Angled Physical Contact) connectors have a fiber connector end face that has been polished at an eight degree angle. When building fiber solutions, be sure to avoid mixing UPC and APC connectors. UPC and APC cannot mate with one another because causes the fiber cores don’t touch. This can cause a degraded connection or none at all.
StarTech.com fiber products use UPC connectors.