Hello, my laptop model is Z50-70. Mine has the Realtek RTL8723BE WiFi chip. The thing is I am getting only around 50Mbps even if my internet speed is 100Mbps. I tested the network speed on my brother's laptop (a Macbook Pro) and he gets 98Mbps.
I would assume your system has the driver already loaded in the kernel, if you are able to establish a network connection and access the net, so lets start with disabling power management first.
If the above wasn't enough to fix it, you can also try these commands which did work for another user on here...
Lets try this in terminal...
sudo iwconfig wlan0 power off
If still not fixed, maybe try this?
sudo apt-get install linux-headers-generic build-essential git
git clone http://github.com/lwfinger/rtlwifi_new.git
cd rtlwifi_new
make
sudo make install
Thats weird, it worked for the other member on here, unless something got changed with that REPO. Are you sure its not just asking for your SUDO password?
I think you do have to have a GitHub account to ask questions etc and the only downside to GitHub now is that it is owned by Microsoft. That's why GitLabs was born as a consequence.