Cat6 U/UTP Cable – Identifying Thread-like Material

Given your comment that it's that it's stranded then i'd suggest going with two plugs and a coupler. If you want to run high speeds then getting a coupler that is actually cat5e rated rather than a generic RJ45 coupler with no internal impedance control is probablly a good idea.

Punch down connections are only suitable for solid cable. Soldering and heatshrinking is possible but will create an impedance bump which may cause issues at higher speeds. The jelly connectors that telephone companies use will likely create an even bigger impedance bump than carefully applied solder/heatshrink and are also unisuitable for stranded cable.

What they call "STP" is "Fully Shielded" -- a per pair shield and an outer sheath shield.

"Compatible" is open to debate. If you want to maintain the panel and cable shielded specs, then no -- as the panel calls for shielded pairs. But just the cable, maybe. You'd have to look at the specs for the cable as those tend to require bonding to a shielded crimp. (or a patch panel that shields each port.)