Try changing to another upstream DNS server in Adguard (such as https://dns.cloudflare.com/dns-query) and see if the problem gets resolved?
alwayssitting
joined 6 days ago
Always had trouble with Nextcloud but ever since deploying it on NixOS it's been rock solid. Both performance and reliability.
Personally I would go for ZFS with the SSD as a L2ARC. But among the options you listed I would do BTRFS RAID1 if you're only gonna use two HDDs, and mdadm RAID5 with BTRFS on top if using three.
It will yeah, although with modern SSDs it really isn't a big problem. I've used an Samsung 840 EVO as L2ARC for 8 years now.