One way to use ethernet is to get a USB 2.0 Fast Ethernet Adapter. You plug your ethernet cable into one end and the other end plugs into one of your 2 available USB 2.0 ports. This is what I did as overall I dislike WiFi unless I'm on my tablet or phone. It still won't be as fast as a direct ethernet port, but it will be better than your WiFi speeds for sure.
I recently purchased an Inspiron 15-3531 laptop about a month ago.  The internet performance over wifi is extremely slow, which is a problem because this laptop can only access the internet over wifi (no ethernet port).  For an idea of how slow an internet speed test puts my download speed at 0.41 Mbps.  My old laptop was clocked tonight via the same ISP and router at 21.45 Mbps download so something is definitely wrong.  Also very strange is the fact that my upload speed on the new Inspiron was clocked at over 10 Mbps?  My router is a Netgear WNR1000 which is compatible with 802.1 b/g/n and works fine on 2 other laptops, a tablet, and 2 cell phones in my house.  The only device experiencing slow internet is the new Inspiron.  I ran a self-diagnostic with Dell's website on the network card and it said everything is fine.  I also updated the drivers from Del's website (even though it said they were up to date) and turned off all the power-saving options related to Wifi.  Nothing has made any difference.  Did I get a computer with a bad wireless card, or is there something else software-related I can do?
Inspiron 15-3531 Slow Wifi with Dell 1506 WLAN Adapter