Can´t get Gigabit connection?

Do you get 100Mbps link speed when you expected Gigabit?

In my experience, it´s always the cable to blame, 9 times out of ten. The tenth time, it´s the auto-negotiation that failed.  Could be solved by unplugging and plugging in the cable again, but most commonly you should switch to a quality cable.

How do you check the link-speed in Ubuntu

verify your ethernet settings (replace eth0 with your ethernet device name – use ifconfig if unsure)

sudo dmesg |grep eth0

you can also install mii-tool and try this

mii-tool -v  eth0

or install ethtool (best) and try

ethtool eth0

Checking actual throughput

use the tool iperf

On one end, start a server:

iperf -s
------------------------------------------------------------ 
Server listening on TCP port 5001 
TCP window size: 85.3 KByte (default) 
------------------------------------------------------------

On the other end

iperf -c 192.168.10.199
------------------------------------------------------------ 
Client connecting to 192.168.10.199, TCP port 5001 
TCP window size: 85.0 KByte (default) 
------------------------------------------------------------ 
[ 3] local 192.168.10.5 port 39994 connected with 192.168.10.199 port 5001 
[ ID] Interval Transfer Bandwidth 
[ 3] 0.0-10.0 sec 1.09 GBytes 936 Mbits/sec

How do you check the link speed in OSX

Start the “Network Utility” appliction

Look at the Info tab, select Ethernet (en0) entry.

See the Link Speed

Also read

http://blogg.fsh.se/2017/03/18/test-and-maximize-network-thruput/