Wrong Link Speed
I had a problem with link-speed between Docsis-modem in front and a OpenWRT-Router. OpenWRT displayed only 10Base-T (10Mbit/s).
It turns out that (against my expections/assumptions) OpenWRT did not support Auto MDI-X (Wikipedia EN: Medium Dependent Interface).
1 # ethtool eth0 2 Settings for eth0: 3 Supported ports: [ ] 4 Supported link modes: 1000baseT/Full 5 Supported pause frame use: No 6 Supports auto-negotiation: No 7 Supported FEC modes: Not reported 8 Advertised link modes: 1000baseT/Full 9 Advertised pause frame use: No 10 Advertised auto-negotiation: No 11 Advertised FEC modes: Not reported 12 Speed: 1000Mb/s 13 Duplex: Full 14 Port: MII 15 PHYAD: 0 16 Transceiver: external 17 Auto-negotiation: on 18 Current message level: 0x000000ff (255) 19 drv probe link timer ifdown ifup rx_err tx_err 20 Link detected: yes
So all you need to change to achieve the intended Link-Speed is to use
- a cross-over cable or
even simpler a (Amazon:) cross-over adapter, which turns some pins of any RJ-45 plug.