Hello,
Switch the router / modem off and on.
Disconnect all devices from your internal network.
It may be caused by an your antivirus program.Disable and try again.
Speed test your net and share your results with us. http://beta.speedtest.net
Make sure you are using the current drivers.
Try playing on different servers,see if it will be the same again.This maybe because of the DNS you are connected to (a server which allows you to connect to the internet provided by your ISP [internet service provider]).It's probably best to try and get a new IP or hopefully a new DNS connection.
-Find out your current IP (don't write here).You can find it out by going here.
-Next time you go to bed, before you do so;turn off your ADSL equipment (including the router or modem - which ever you use). Leave them off over-night.Only turn them back on when you want to use the internet.
-See if doing this changes your IP.If it does try step 3 below.If it hasn't changed,try step 3 but I suspect you'll be better off going to step 4.
-Then try ETS2 multiplayer and see if the problem persists.
-If the problem persists,contact your ISP and ask them to put you on a different DNS server connection with a new IP as you are having issues downloading and uploading,and especially games