My impression from internet in Amed from 12 months ago:
No 4G (3G only). didn't do to many speed tests. I estimate, that average speed was 3-5 Mbit/s (for Wifi and 3G)
Skype should be possible, but in the end most Wifi around Amed is inconsistent.
So it might work the first day, but have issues the second day.
I am also into freediving and I am going to Phuket for Dec/Jan instead of Bali exactly for the reason of sloppy internet in Bali.
Send me a DM, maybe Phuket is an interesting alternative for you