This guide helped in my case: https://connectwww.com/how-to-solve-realtek-rtl8723be-weak-wifi-signal-problem-in-ubuntu/4625/
My problem was that my wifi card had 2 antennae but only one was plugged in and the linux drivers were using the wrong one. This downloads new drivers and changes the
ant_sel option to 2.
git clone https://github.com/lwfinger/rtlwifi_new
sudo make install
sudo modprobe -rv rtl8723be
sudo modprobe -v rtl8723be ant_sel=2
If it doesn't solve the problem, try with
sudo modprobe -v rtl8723be ant_sel=1.
If the problem was resolved, then use this command to make the change permanent across reboots:
echo "options rtl8723be ant_sel=2" | sudo tee /etc/modprobe.d/50-rtl8723be.conf
ant_sel=1, as the case may be).
Be aware that some updates replace the above configuration and so you might have to change this periodically. I made a bash script in my
home with the above commands (minus the
git clone part, of course) and run it when I see that the internet is unbearable slow.
Also, you might want to try disabling bluetooth. For some reason my laptop cannot connect on the internet if BT is enabled.