Connecting an Raspberry PI to the eduroam or campusroam wifi network results in intermittent connections on Raspbian Buster.
Following tutorial explains how to fix this issue, a working internet connection is required!

Add one of the following lines to your '/etc/apt/sources.list' file. Comment out previously existing lines with '#'

Pick 1 out of two lines!

deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
deb http://raspbian.raspberrypi.org/raspbian/ jessie main contrib non-free rpi
#Note: copy pasting in a terminal using the keyboard shortcuts requires an additional 'shift' --> 'ctrl + shift + c' or 'ctrl + shift + v'

Run 'sudo apt-get update' to complete the previous step.

Full example

Full example

sudo nano /etc/apt/sources.list                                                    #Type this command in cmd, followed by 'enter' to open the file in nano
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi    # paste this line using 'ctrl + shift + v'
 
# Use the '#' in front of previous existing lines to comment them out!
# press 'ctrl + o' to save the file!
# press 'ctrl + x' to exit nano!
 
sudo apt-get update                                                                # Once existed, continue with updating aptitude to make the changes take effect. 

The previous step should have downgraded the 'wpasupplicant' versions available for installation on your system. Run a check using 'apt-cache policy wpasupplicant'
Follow the previous step with 'sudo apt-get install <package of choice>'

Type:

apt-cache policy wpasupplicant                                                     # this prints the wpasupplicant versions available on your system. 
 
# Select one of following versions (stretch or jessie). Selection is based on your config inside /etc/apt/sources.list
# Note that the version numbers could be different on your system! Check the apt-cache policy wpasupplicant output for certainty! 
sudo apt-get install sudo apt-get install wpasupplicant=2:2.4-1+deb9u7 -t stretch  # package of choice is printed by the previous command.
sudo apt-get install wpasupplicant=2.3.1+deb8u10 -t jessie                         # package of choice is printed by the previous command.

Note: The print-screen was taken after downgrading wpasupplicants on my system!

Open up the /etc/wpa_supplicant/wpa_supplicant.conf file using nano.

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
# press 'ctrl + o' to save the file!
# press 'ctrl + x' to exit nano!

Add additional lines to the file:

| wpa_supplicant.conf

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=BE
 
network={
         ssid="campusroam-2.4"
         scan_ssid=1
         mode=0
         proto=RSN
         key_mgmt=WPA-EAP
         eap=PEAP
         identity="u******@kuleuven.be"
         ca_cert="/usr/share/ca_certificates/mozilla/DigiCert_Assured_ID_Root_CA.crt"
         password="*******" # Ask google if you want this encrypted.
         phase1="peapleabel=auto peapver=auto"
         pahse2="auth=MSCHAPV2"
}

# press 'ctrl + o' to save the file!
# press 'ctrl + x' to exit nano!

Reboot your system!

First make sure you have network connection using ip a.
Secondly if you're connected, check your current DNS settings using 'cat /etc/resolv.conf'

ip a
cat /etc/resolv.conf

Use nano to open the '/etc/dhcpcd.conf' file add the following to it: 'static domain_name_server=8.8.8.8 134.58.126.3'

sudo nano /etc/dhcpcd.conf
static domain_name_server=8.8.8.8 134.58.126.3  # change the secondary '134.58.126.3' ip address to one of the addresses shown inside your '/etc/resolv.conf' file. 

Reboot your system!