Ubuntu – How to make WiFi signal stronger on Ubuntu 16.04 LTS with Realtek RTL8723BE

So, I figured out what the problem was. Since my machine runs on a UEFI BIOS with secured boot enabled, all the drivers that can be loaded onto the driver stack must be "signed". I think in kernel 4.4 Ubuntu, they enforced this sign verification quite strictly. That being said, all I did was to disable the secure boot from my BIOS setting (won't say this is a permanent solution) and now the wifi works like a charm.

Finally I was able to fix the issues after trying out numbers of different methods.

1. Get details of your PCI wireless card by running sudo lshw -class network

2. Get your card model info according to the product line.
   For instance, as you can see in the question description it says
   product: RTL8723BE PCIe Wireless Network Adapter so the model of my card is RTL8723BE

   Or product: RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller so the model of my card is RTL8101/2/6E

3. Give the permission sudo chmod 755 /etc/pm/config.d/

4. Open or create config and add SUSPEND_MODULES="rtl8723be"(replace rtl8723be with your own model number)
   Then run
   echo "options rtl8723be fwlps=N" | sudo tee /etc/modprobe.d/rtl8723be.conf
   (note that when replacing rtl8723be with my card which is RTL8101/2/6E i should only type .../modprobe.d/RTL8101.conf; and /2/6E shouldn't be written)

Finaly restart your system.

Now your system should be able to reconnect automatically after sleep, and wifi connection never got lost once for me after doing this.

"The up/down arrows is likely a network manager bug that results in network manager thinking the wifi device is actually ethernet.", according to Jeremy31.see bug info here You should be able to fix it by installing NetworkManager-1.2.0.

Thanks to Jeremy31 for providing the solutions.