(1) I entered a hostname and IP in LuCi under Static Leases like this,:
   DNS-325     <MAC address left blank>    192.168.1.250    <leasetime left blank>  <ip6 suffix left blank>
But the router completely refuses to provide the above DNS mapping to clients.

(2)    THEREAFTER ON MY PC:
C:\Users\user>nslookup
Default Server:  zero.private.lan
Address:  fd11:5fcc:b8db:10::1

> DNS-325
Server:  zero.private.lan
Address:  fd11:5fcc:b8db:10::1
*** zero.private.lan can't find DNS-325: Non-existent domain

> DNS325.private.lan
Server:  zero.private.lan
Address:  fd11:5fcc:b8db:10::1
*** zero.private.lan can't find DNS325.private.lan: Non-existent domain
> quit

C:\Users\user>ping 192.168.1.250

Pinging 192.168.1.250 with 32 bytes of data:
Reply from 192.168.1.250: bytes=32 time=4ms TTL=63
Reply from 192.168.1.250: bytes=32 time<1ms TTL=63
Reply from 192.168.1.250: bytes=32 time<1ms TTL=63
Reply from 192.168.1.250: bytes=32 time<1ms TTL=63

Ping statistics for 192.168.1.250:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 4ms, Average = 1ms

C:\Users\user>

(Last edited by snovotill on 23 Mar 2018, 02:20)

Enable logging on the router's dnsmasq, and see what is happening.

Damn it the thing started to reply to DNS queries soon as I added "log queries" to the config files. There must have been a bad EOL character in one of /etc/dnsmasq.conf or /etc/config/dhcp
Good advice eduperez and I thank you for that. On to other things now lol.