LOS & PON flashing lights

[#1]

Hi
Does anyone know what flashing LOS & PON lights actually means?
We have had several loss of connections in the last few days, where the LOS & PON lights just start flashing.
Then, later in the evening, everything just starts working again.
My guess is engineers messing with stuff further up the PON, but nothing to back this up with!
Thanks
GunSmoke

[#2]

LOS - Loss of signal
PON - Passive optical network
I'd suggest that the flashing is an alarm state showing signal failure...

[#3]

that much I figured!
I'd wondered if it was a specific type of problem, or a common fault
GunSmoke

[#4]

http://www.cyberbajt.pl/download/Huawei/GPON/Manual.pdf
Table 2-14 on page 22