I wrote about a lot of fun getting a system to work with static IP addressing (it is running Debian 10 with LXQt). Since it was able to be made to statically configure its IP with no issues, I configured the other Debian10-LXQt system with a static configuration also. The second computer only has one network adapter, but the benefit is that since the network router and wireless broadband router are only switched on when needed, I do not need to wait for the network router to come online each time and be ready to supply DHCP addresses to the client computers when they start up. Everything is working well now.
At the present time the backups are all being done locally on each computer as previously referenced using rsync since I have yet to do further work to make an rsync daemon function as planned for trial for backups. Another option I could look at for backups is the BackInTime application, however I have been generally wary of using anything that does not do straight file by file backups to the destination but instead creates its own archive format. This is not such an issue with commercially supported proprietary software, but I am very insistent that I do not get locked into archive formats with open source software that may not be supported forever. Probably this is the reason why lots of people prefer just to use rsync.
mainpc had an issue a couple of weeks ago when some sort of timeout on one of the RAID array disks caused mdadm to push it out of the array. It was then coming on and off line seemingly randomly for a time, but then stabilised and stayed online. Smartctl testing showed there were no errors on it. After a week it was readded to the array which is now functioning at 2 disks again seemingly with no problems. However as these disks are 4 years old (last replaced 2016) I am currently planning to buy 2 new disks for the array as soon as I can, this will be at the rate of 1 disk per month with the old ones being available for backups although it would still be preferred to buy completely new backup disks.
The disks in the array currently are WD Black and that is the proposed replacement at $250 each. SSD is considerably more expensive but by the time I next have to replace any of these disks the cost of SSD could well have come down and be more affordable. WD Black SSDs in the size needed are very expensive at around $1000 regular pricing each (four times the HDD price) and are only M.2 format which is problematic since it is rare for a board to have more than one M.2 slot at least in the price range I have. I have checked and the H-97 and B250M-D3H boards do have one M.2 slot each but not two. There are adapters available but another option is simply to switch to another SSD brand such as Intel which is considerably cheaper although with lower performance, if the performance at least equals standard HDD it would be a big reduction in cost to around $400 each. As I think, in a few more years getting a pair of SSDs for the array will be within the same price range as the regular HDD. I am still keeping the lid on the amount of storage on this computer resisting the temptation to buy bigger disks as in spite of growing photo and general data storage, so far it has proved possible to manage existing storage sufficiently well to avoid running out of space.