I have an Ubuntu 16.04 server connected to a switch and they negotiate a half-duplex connections instead of a full-duplex, and I don't know why. I have tried using another port and cable (which another server uses to successfully connect through full-duplex) but problem persists, so this rules out a cable or switch port problem and I assume that the problem is related to Ubuntu configuration or to the NIC.
# lspci | grep Ethernet 02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5722 Gigabit Ethernet PCI Express # mii-tool -v eno1 eno1: negotiated 1000baseT-HD flow-control, link ok product info: vendor 00:50:ef, model 45 rev 0 basic mode: autonegotiation enabled basic status: autonegotiation complete, link ok capabilities: 1000baseT-HD 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 1000baseT-HD 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control link partner: 1000baseT-HD 1000baseT-FD 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
Any ideas about how to fix this and get a full duplex connection (1000baseT-FD)? I don't like forcing the link to 1000baseT-FD, I would prefer to fix/debug autonegotiation so that this mode is automatically selected.