I get 550Mbps on 5 ghz (80Mhz wide) with my iPhone 13 and I get 800-850Mbps on an iPad pro on 6Ghz (160Mhz wide). When in the same room as the AP. When not in the same room speeds are a bit all over the map.

This is via the speedtest.net app on a 1Gbit fibre connection.

I am using new U7 Pro Wall APs.

RAID isn’t backup it is high availability.

40 drives ? Why that is a huge amount of power , what is your space target

RAID 1 ? With 40 drives ? That would be absolutely stupid you want to use RAID 6 or 10 so you don’t waist 50 % of your space with RAID 1. Or some other N+2 disk redundancy.

Have you considered how much power such a large setup will need?

iSCSI is block level storage where NFS/SMB are file level… When you browse a folder with SMB/NFS it is going to ask the remote service for the meta file list then cache the whole thing till it thinks it needs it refreshed… iSCSI is going to go read a set of blocks to read the metadata off the remote file system. iSCSI can be considerably more chatty between the two hosts as it is lower level.

• If having dedicated interfaces / subnets is needed for improved bandwidth
• If you want to have a network segment with jumbo frames (you often don’t want this on the general network interfaces)
• If the network protocol creates substantial network noise iSCSI / block level protocols tend to be very noisy. Vs file level ones like SMB or NFS

Simple answer would be to attached the pi to the router via the router Ethernet port on the LAN side and learn how DHCP and DNS work.

Pi-hole is primarily a forwarding DNS server that filters DNS requests