I was on this topic
recommended to open an FR here.
I have Pihole running on an armv5l nas.
When updating to v5 it was noticed that it was not updated correctly because the FTL service is not available for the armv5l.
Before v5 I solved it by compiling the pihole-ftp myself.
root@Qnap-NAS:~# cat /proc/cpuinfo processor : 0 model name : Feroceon 88FR131 rev 1 (v5l) BogoMIPS : 1974.27 Features : swp half thumb fastmult edsp CPU implementer : 0x56 CPU architecture: 5TE CPU variant : 0x2 CPU part : 0x131 CPU revision : 1 Hardware : QNAP TS-41x Revision : 0000 Serial : 0000000000000000