This is normal for Starhub Maxonline,due to the technology they
use(Hybrid Fibre Co-axial) you do not get a dedicated line as it(a
very large one) get shared by one block or area.
For Singnet, they use the older Twisted Pair which goes through
the phone line.The advantage is that you enjoy a dedicated line so
your bandwidth is unaffected by traffic(not as much as Starhub at
least) and hence faster speed.
The disadvantage is, the stability of twisted pair is not as
good as HFC.There is reports of certain Singnet areas where
disconnection/disruption issues is encountered commonly or
rarely.In contrast,Starhub Maxonline is stable with very very rare
disconnection/disruption isses.
So its up to you if you want stability or speed.My starhub has
never encounter a disconnection nor disruption for years until it
happened a few days ago,and even so in the middle of the night.