A flashing PON light is the ONT and OLT ( headend ) ‘handshaking’ basically its the authentication protocol of the ONT being allowed onto the ‘network’ , in layman’s terms , the ONT is asking to be connected, the headend is replying ‘ hang on while I check you are a valid ONT ‘ once the authentication is done , the PON light goes steady green , if the OLT he no ‘record’ of the ONT serial number , authentication would fail and the PON light would never go steady green but continue to flash …it’s not likely that there is a situation where the headend data were somehow corrupt and ‘forgetting’ only your serial number, causing a new authentication cycle just for you while leaving all other members on the PON working without issue .
As you seem to have had the ONT replaced (that’s what I would have suspected as the problem ) that effectively removes the ONT from the list of possible faulty components , however your service is optically identical to all the other users on your ‘PON’ its difficult to see how a headend /OLT problem would only affect you and not all the other users (potentially 30 users in total) , you could be the only customer on the PON , or the only one to have reported it of course.
Was the power unit replaced at the same time as the ONT ? , it’s possible (but not really that likely) if the power drops , even if it’s only momentarily, the ONT and OLT will go through the authentication process each time , although the varying times to re authenticate your connection don’t seem to align with power ‘blips’ and you would also expect to see the power led go off and back on ….any issues in general with the power supply to the address ?
The authentication part of the network has nothing to do with your ISP , even if you stopped being a customer of anyone , the ONT would stay ‘connected’ to the headend , so whatever the issue is , it’s within Openreach’s domain , nothing to do with BT ….there is no ‘routine’ or scheduled maintenance that would cause this failure.
Do you know if any close by neighbours are on Openreach FTTP , connected to the same PON even if they were with a different ISP , optically you are identical , the same aggregated data arrives at all ONT’s , it’s the individual ONT that respond only the ‘ data packets’ addressed themselves, ignoring everyone else’s data …so if it were the headend ‘falling over ‘ , all users would see the outage not just you , perhaps ask if anyone really close by is experiencing the same issues .
