Not sure this is the right forum for this particular topic, but here it goes.

First, some background info:
I work for a recycling company/thrift shop chain. Earlier this year I was added to the already running PC-refurbishment project. Officially this consists of 3 blokes, including yours truly, but one is a web designer and hasn't visited the premises housing the project since he'd introduced me, the other chap is a volunteer with ADD and an addiction who uses it as some sort of rehab. Meaning that effectively, I'm running the place.

Hardware is donated by private individuals but also (semi-) commercial enterprises as well as governmental dept's (including UN tribunals, which are/were located in or in the vicinity off my home town) and ranges from Lenovo Intel-based Core2 systems (sans hard-drive and RAM) to Dell P4's. I even have a P3 server (2U, SCSI-based) set aside as the drive is too small (70GB is not enough).

When I started out, Linux Mint was used to install Linux on whatever hardware was picked. Imagine the "joy" of systemd on a P4 :-\  We were lucky to install 2 systems a day!  A few weeks ago I made the decision to switch over to Devuan instead. Regrettably, for a novice the default DE is too spartan, so I wanted Mate instead. But that can't be installed from the install DVD (missing policykit packages) as well as quite a few machines can't boot from DVD at all. So I decided to create a local mirror. Fortunately I found enough network stuff to make it happen (switches, machines with sufficient space to host everything one needs for an offline mirror) as our location has no internet connection! Not having done this before it took a fair few days to fiddle everything and get a working system. Next step, obtain the packages from the Devuan mirrors. That went reasonably well, copying the lot over also worked. But after the first week, I got reports that the mirror was outdated and therefore would not be used to install stuff from. This was traced to a just-under-a-week TTL of the various Release files. That in turn meant I need to take the server home every weekend to update it and bring it back in on Monday. Cumbersome. Quite. So, how do I prevent these low TTL files messing things up as it's my intention to inform purchasers of these systems they need to update their PC's after connecting it to the web first thing. Ideally, I'd like to see no TTL at all and I'll update the repo on a monthly basis in order not to get too far out of sync with the main Devuan repo's.

(FYI: I'm running Linux exclusively since 2005, initially Debian after earlier testing of RedHat 8&9 and Suse, but when the last pre-systemd version became too old I switched to Funtoo in 2015. Regrettably Portage is not as good in conflict-resolving as the Debian package managers, so when I learned about Devuan I made the switch when Portage threw me one too many wobbly updating my system :-\ )

Thanks if you've read it this far