Behavior could be dependent not only from the module, the lists chosen, but also on the availability of the servers providing lists.
Therefore, maybe for months something outside your setup did not change and yesterday did.
Obviously this not help easing the situation o make go away the undesired message, but maybe on this NethServer theres not much you can do.
How to figure it out if something can be done or not? Via the logs. Lists are downloaded via http, which has got a lot of errorcodes telling why you can’t have the file the installation asked for.
(adding TLS don’t change the protocol answers)
For telling about a possible comparable scenario…
This installation was not able to retrieve updates. Other three installations on the same site were able. At first glance, I considered as cause of issue the mirrors system, blocking connections to my setup “suddenly”.
That was not the real cause of the issue: the firewall appliance in front of all the installation was limiting the number of connection for that installation (via IPsec monitor quite different devices on other 5 sites) so…