A few months ago we wrote an article in which we explained how to access the Apple AirPort Extreme / Time Capsule disk from Linux. Although they should be easily accessible from Samba, Apple has not updated its routers to be compatible with the new versions of the protocols, so it had to be instructed to use the old one in order to access their content. But everything in the world advances, and with Linux 5.15 Those of us who in the past used more macOS and apple devices have a problem again.
Among the novelties of Linux 5.15 we had one that implemented an SMB3 server called ksmbd. What at first was not so in sight was the end of a support, as explained here, without the one NTLM can no longer be used and weaker authentication systems. Therefore, when we indicate the sec = ntlm option at mount time, it cannot move forward and shows us an error.
Linux 5.15 drops support for NTLM
At the moment, what is being said in the different forum and reddit threads that I have seen is that the end of support is here to stay. If we want to continue accessing our shared AirPort Extreme disk from Linux as we did until now, we will have to stay on Linux 5.14 or some older kernel. This will be easier in distributions such as those that have tools with a graphical interface to choose which kernel we want to install. For those of us who may have several and do not want to lose this option, it is best to leave Linux 5.10 installed, which is LTS, for when we want to access our AirPort disk.
Another option, that I have not had time to study in detail (soon there will be an article) is to use afpfs-ng to mount the unit, but it is software that has not been updated for a long time and does not get along very well with the latest versions of file managers: although it mounts it successfully, Dolphin tends to hang, but in Nautilus it seems to work. In case this fails us, it is best to keep Linux 5.10 in the bedroom.