Information:
The LANCOM access switches of the types GS-3510XP and GS-3528XP have, among other things, Ethernet downlink ports on which maximum transfer rates of 2.5 Gb/s are possible.
However, if network components are connected to these ports via PoE and the CAT cabling has been incorrectly selected (e.g. unshielded CAT5 / UTP cable), it can happen that a maximum of 1 Gb/s is transmitted on these ports . "Aliennoise" disturbances caused by radiation from unknown sources.
The downshifts from 2.5 Gb / s to 1 Gb / s always occur during runtime. The link is initially negotiated with 2.5 Gb/s, but at some point it drops back to 1 Gb/s during operation.
LANCOM Systems therefore recommends the use of shielded CAT5e or CAT6e Ethernet cables (each of the type STP or FTP) in order to minimize the risk of a downshift from 2.5 Gb/s to 1 Gb/s.
Further technical information on this topic can be found in the NBASE-T Alliance whitepaper at:
https://archive.nbaset.ethernetalliance.org/wp-content/uploads/2017/05/DownshiftWP_051517.pdf
