Why did clients drop out?

Question

linux

We have an openvpn router on Mikrotik. The certificate is generated on it, ca and clients
On clients - ubuntu 16.04. The connection goes through the domain name. I checked it - everything is ok, it's valid, it's paid, it gives the right IP

. Today, clients have massively fallen off the server. And they don't come back.
More than 300 clients, scattered throughout the Russian Federation, dns servers everywhere 1.1.1.1 and 8.8.8.8

Deployed the client image on a virtual machine at home, and in a data center (rented vps). Everything is ok, everything works / connects.
UPD
Clients on Windows - 7 and 10 - work fine
Clients on Mikrotik - work fine
Clients on ubuntu18 (raspberry) - only 50% fell off (approximately)
images are the same EVERYWHERE!!! A "standard" was made from which machines were stupidly cloned, and nothing changed

there. Any ideas ??
UPD - gave access to one of the points - restarting [email protected] helped. stupidly was in the status of failed .... I don’t understand at all

UPD
clients have already begun to appear, the cant was clearly with DNS (the cache was apparently updated), but using an ip address to connect is also not an option, the server sometimes moves ...

Answer 1

Roskomnadzor messes around with dns change, blocked

Answer 2

So maybe their certificates have expired?

Answer 3

It may not be entirely applicable to the described case, but I recommend starting to prepare for blocking any VPNs on TSPU. Look for workarounds, develop fallback scenarios...