I'm using Kubuntu18.04 and whenever I use Firefox with the Ethernet cable connected or without I get the same download speed. But with Falkon download speeds are 30mb/s faster and upload speeds are 10mb/s slower. Also if I turn WiFi off and try to use either web browser they don't work. So what I'm asking is how to tell if Ubuntu is using Ethernet or WiFi and if not using Ethernet how to make it use Ethernet.
Thank you for reading.
Ubuntu will use both your Wireless and your Ethernet at the same time. I use a program called vnstat for Internet traffic monitoring:
$ vnstat
rx / tx / total / estimated
wlp60s0:
Apr '18 20.83 GiB / 1.55 GiB / 22.38 GiB
May '18 4.33 GiB / 5.34 MiB / 4.34 GiB / 11.36 GiB
yesterday 404.97 MiB / 509 KiB / 405.47 MiB
today 593.05 MiB / 773 KiB / 593.80 MiB / --
enp59s0:
Apr '18 206.79 GiB / 56.90 GiB / 263.69 GiB
May '18 63.19 GiB / 13.34 GiB / 76.53 GiB / 200.60 GiB
yesterday 6.73 GiB / 817.44 MiB / 7.53 GiB
today 4.03 GiB / 376.32 MiB / 4.39 GiB / 5.31 GiB
Today the WiFi (wlp60s0) has sent/received 593 MB and Ethernet (enp59s0) has sent/received 4.39 GB.
To setup vnstat see this Q&A: How to track the total network data in a month
You don't have to tell Ubuntu to use Ethernet over Wifi because it automatically uses the fastest connection. The exception being if your Ethernet is 100 Mbps and your WiFi is faster than 300 Mbps. In this case the WiFi would take precedence.
If your WiFi is faster than your Ethernet click the Up/Down arrow representing network connection in the Systray. From the drop down menu disable the WiFi link by clicking disconnect button. You can also disable the Ethernet link from the same drop down menu.
Check which interfaces are connected, and which are not:
$ sudo lshw -c network | egrep 'description|name|link'
Interface is connected if link=yes
Monitor the traffic on connected interfaces:
$ watch ip -s link
Look for interface names, after 1: 2: 3: etc. Ignore lo as this is loopback interface (What is loopback?)
