So I would not be stepping on Zen’s toes or impacting my Zen FTTP connection in anyway?
And if so, would this be a good way to rule out anything physical? In other words, would it mean that I could have new fibre spliced at the CSP (thus ridding myself of the niggling, albeit irrational, suspicion that my problem is linked to a poor/badly spliced cable?)
If there was dodgy splice in the CSP your service would have worked , albeit potentially periodically , and occasionally you would see the LOS light lit ( los of signal) ,a dodgy splice isn’t going to be the issue .
Your ‘end’ needs no further investigation, you have had a change of ONT , the light levels are apparently fine , and your ONT is authenticated on the PON , whatever the issue is , it’s between the OLT and the handover point into Zen or the wholesale provider that Zen use.
Ordering a second service before the first has been correctly provided is of no concern to your initial order , if it gets installed and works before Zen sort out their service to you ( no prejudice from me , it could be an OR or Zen problem ) it wouldn’t really indicate where the first service issue is, but you could be in a situation where you have two services and getting rid of the one you don’t want costs you early termination fees.