Hello,
Im in the process of replacing honeywell sundial rf2 (DT92E & ST429C ) to Nest V3 S Plan.
Ive successful ( i think) wired up the nest link correctly.
N to N
L to L
Jumper from live to 2 then 2 to 5
Heating into 3
Water into 6
E to E
The nest thermostat is up and running looking nice...