For legal and sanity reasons, there’s no classified stuff here. To anyone from work: Yes, I fixed it. Crisis averted, lesson learnt.

This is mostly a note to self in case I try to fix this issue when it happens again, and I need to revert everything.

Problem

WiFi works 10/10 on work laptop. VPN works 5/10. It connects, works for a few minutes and then it just stops working. Even after disconnecting from VPN, WiFi does not work normally and a system reboot is needed.

“My VPN does not work. I can’t take WFH.”
“MY VPN DOES NOT WORK TOO!!”
- 2 colleagues (who also happen to have Ubuntu)

The above is a testimonial to the issue not being unique to me.

Problem Pt. 2

Having, SOMEHOW by sheer brilliance (read: Stack Overflow), fixed the above issue, when I log in at office on the internal WiFi, I cannot access the internal services. VPN works completely fine, though.

Cheap Fix

Restarting Network Manager and systemd-resolved service fixed the issue but felt like hitting a drained TV remote to juice out a few button presses. A permanent fix was needed.

Resolution

The issue lies with the systemd-resolved which provides DNS resolution to applications. There’s a symlink created to /etc/resolv.conf by the service for domain name translation through the nameservers provided.

• Fix which worked for me was deleting the symlinked resolv.conf and manually adding the nameservers. Restarting systemd-resolved and NetworkManager fixed the issue and VPN and WiFi worked completely fine then, as expected.

• Another fix I had tried to implement but did NOT work for me was replacing the line in the file /etc/ppp/ip-up.d/0000usepeerdns:

cp -a "$REALRESOLVCONF" "$REALRESOLVCONF.pppd-backup.$PPP_IFACE"

with

cp "$REALRESOLVCONF" "$REALRESOLVCONF.pppd-backup.$PPP_IFACE"
chmod 644 "$REALRESOLVCONF.pppd-backup.$PPP_IFACE"

This solved all my VPN and WiFi problems till I visited office on a Monday morning.

Resolution Pt. 2

It was a frantic attempt at fixing the WiFi issue because I could ONLY connect to internal services with VPN on and even internal office WiFi did not work for it. I had to undo what I had done but I couldn’t put my finger on what it was.

• I reverted the change in the 0000usepeerdns file but it did not solve my issue.
• I moved back the symlinked resolv.conf but it STILL did not fix my issue. The symlink was gone and needed to be created again.

The good old reinstall came in clutch.

sudo apt remove --purge systemd-resolved
sudo apt install systemd-resolved

A Network Manager restart right after this created the symlink again and fixed the issue.