Comment 127 for bug 1589401

Same issue on arch.
As a workaround you can create this systemd unit :

[Unit]
Description=System resume actions
After=suspend.target

[Service]
Environment=XAUTHORITY=/home/user_name/.Xauthority
Environment=DISPLAY=:0.0
Type=simple
ExecStart=/usr/bin/bash -c "killall nm-applet && sudo -E -u user_name /usr/bin/nm-applet"

[Install]
WantedBy=suspend.target