Thank you so much for your support.
I understand the work on 20th and the outage on 18th have nothing related with each other.
For the outage on 18th,
Which port did the reset?
Was it LAN switch port at customer site facing customer router?
How was the ping test result? (from where(IP) to where(IP) you did ping test)
From what time to what time they performed the ping test?
For the maintenance work 20th,
Why you didn't send prior notification to Singtel for this circuit? ( Singtel did receive notifications for other customer circuit, but not on this customer)
there may be some un-updated info on your(or UIH's) database as this circuit is migrated from TOT to UIH on Apr-5.
Would check it and give us some preventive measure?