Solo workation trip to SE Asia

So this month I want to spend atleast 3 weeks somewhere in SE Asia. I've never been. Where should I go? Here are a few criteria for me

1. Has to have good internet connectivity (open to buying a phone connection. Wifi prevalence should be common)
2. Near water or hills or both.
3. Monthly rent under 45000
4. Should have decent exploration activities (treks, hikes, lakes)
5. Not completely isolated. Should have a decent digital nomad crowd but not overcrowded af

Please share your thoughts. I really want to gtf Outta here fast