Which Internet provider is the cheapest in Singapore?

I will fly to Singapore in a few months and will stay there for 10 days. I surf a lot and will take my cell phone and laptop with me. What would you recommend me to avoid roaming fees? I was thinking of buying a contract-free mobile Wi-Fi router here in Europe. Is that recommended or is it not worth it? If so, which mobile WLAN router is recommended? Which Singaporean internet provider would you recommend to me?

Briefly switch on the cell phone on site, then in flight mode.

Use Wi-Fi in the hotel and Wi-Fi in the restaurants.

You are not in Germany, Asia is very far ahead in terms of open Wi-Fi.

So if you don't have to make a phone call, that's enough.