Install Realtek rtl8723be Wifi Drivers in Ubuntu.

First of all make sure that the necessary packages are installed.

 $ sudo apt-get install build-essential git

Then, clone the lwfinger/rtlwifi_new repository and checkout the rock.new_btcoex branch.

$ git clone https://github.com/lwfinger/rtlwifi_new.git
$ cd rtlwifi_new
$ git checkout rock.new_btcoex

Now, build the drivers and install the modules.

$ sudo make
$ sudo make install

Then, reboot your system.
Open /etc/modprobe.d/
Create a file rtl8723be.conf
Put the code below in it, where X is your antenna number.

options rtl8723be fwlps=N ips=N swlps=N swenc=Y disable_watchdog=1 ant_sel=X

In my case, ant_sel=2 provided a lot more networks with much higher signal strength than ant_sel=1. Finally, you can append the correct ant_sel parameter in your /etc/modprobe.d/rtl8723be.conf.
And then you need to reboot or manually reload the driver.

$ sudo modprobe -rv rtl8723be
$ sudo modprobe -v rtl8723be

I hope this helps!
Thanks. 🙂