Setup for local network (LAN): client yes or no?


What setup would you suggest for a ~30PC/Laptop environment with ~60 users that would like to collaborate? Yes, not everyone is using a device all the time.
Total Files ~1TB right now.
Internet connection is really bad, and it is more important that file access is fast within the office than in home office, so local server is preferred.
Accounts: at the moment there are only 3 accounts based on roles. Personal files are stored in /Personal/Name/ which is shared across the three accounts. It would be good if everyone could login with their individual name/password (like Active Domain), but then you have to setup the NC Client by hand for each machine and user > No.
There is a mix of machines: Windows 10 and Linux (Mint, could be switched to Ubuntu etc if needed).

Scenario 1: Nextcloud on a local server, all devices use the sync client via LAN(1GBps). Continue to use 3 role-based accounts (= local accounts on every machine)
(-) files are synced to all machines, even multiple times when there are multiple users per machine, so every machine needs a ~4TB drive… (only syncing some directories is not an option because then nobody knows that more dirs exist). waste of resources & money.
(-) regular file conflicts because file locks are not synced

Scenario 2: Nextcloud on a local server, all devices connect via webDAV. individual account management via ldap, hopefully webDAV integration can be automated per user. (ManageEngine? Filewave?)
(+) Files only stored once, on server. Cost effective.
(-) I heard webDAV is much slower than Samba or NFS
(-) regular file conflicts because file locks are also not synced in Nextclouds webDAV implementation

Scenario 3: Use Seafile locally instead because it automatically locks files when they are edited.

… Or something else? Use Samba locally and somehow connect it to Nextcloud only for file access when outside of office?

bump Anyone got any ideas/experience?

Good topic with great Idea.