have you found and tried those ones here?
- No apps anymore shown in the administrator "+Apps" page - #2 by Giuseppe ?
- AppStore is empty - #4 by SmallOne ?
- App pages available but plugin are not visible nextcloud Hub 18
i can’t give you more hints since you deny to give out more infos about your server, your settings, your configs, logs… etc.
maybe even raspi 2b+ is getting too overloaded with nc… i dunno. all i know is: i wouldn’t wanna like installing it on a raspi 1, now,
you’re right - step by step. first solving first problem.
but in general… i experienced the same thing with some “untested” apps in my instances… i removed (de-installed) them and then they turned up anew and i could re-install them without any flaws. but again: get first problem done first.