I am using Debian Stretch/Testing with Xfce. I have an eight year old Acer laptop. I am currently using network-manager-gnome to connect to WiFi from the laptop at the university where I teach. Most of the time I have no issue. However, something strange has been happening. On Mondays, only on Mondays (every Monday for the past three weeks). My connection will work for about two to three minutes, and then it will slow to a halt. It actually did the same thing today when connected to a WiFi hotspot I created on my phone. My phone works fine on the university WiFi at these same times. Today, while using network-manager-gnome, my WiFi hotspot connection died. So I disabled Network Manager and I connected to the hotspot via manual configuration. This WiFi connection worked perfectly fine. For manual configuration I have the /etc/network/interfaces file that sources to the interfaces.d directory. I have created /etc/network/interfaces.d/wlan0. It has content like this: auto wlan_homeiface wlan_home inet dhcp    wpa-ssid home-network-ssid    wpa-psk secret-keyauto wlan_hotspotiface wlan_hotspot inet dhcp    wpa-ssid wifi-hotspot-ssid    wpa-psk secret-keyTo connect I use the command (example of home network):sudo ifup wlan0=wlan_home(I of course have the proper r/w permissions (chmod 600) set to the wlan0 file as well as a generated key instead of my actual password.) Now to my question. I would like to add the proper configuration information to the wlan0 file to be able to connect to my university network. I would like to be able to connect using this manual configuration for when Network Manager fizzles out. Here is the general information used to connect in nm-connection-editor. I have been unable to find any guide on the proper connection information to place in my file. Otherwise, perhaps the only option is to set up the connection with the wpa_supplicant.conf file. 
Manual Configuration or WPA Supplicant for WiFi on a University Network
networking;wifi;network interface;networkmanager;wpa supplicant
Here is what I have for my /etc/network/interfaces file. # This file describes the network interfaces available on your system# and how to activate them. For more information, see interfaces(5).#source /etc/network/interfaces.d/*# The loopback network interfaceauto loiface lo inet loopback# The primary network interfaceallow-hotplug eth0iface eth0 inet dhcp# Wifi network interfaceallow-hotplug wlan0#iface wlan0 inet manual #   wpa-roam /etc/wpa_supplicant/wpa_supplicant.confiface wlan0 inet dhcp    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf#iface default inet dhcpAbove you see the lines with iface wlan0 inet manual and below it wpa-roam... commented out. With this setting my wifi would not reconnect after system suspend without rebooting. Here is my setup for the /etc/wpa_supplicant/wpa_supplicant.conf file.ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdevnetwork={    ssid=University-Network-Name    scan_ssid=1    key_mgmt=WPA-EAP    identity=my-username    password=secret-password    eap=PEAP    phase1=peaplabel=0    phase2=auth=MSCHAPV2    priority=30}network={    ssid=home-ssid-name    psk=secret-password    priority=40}