WEF 1 April 2017, Singapore started the shutting down of 2G network and the deadline given to all the telcos for completion was 18 April 2017.

Make sure the mobile network for your Hotlink card is not set to 2G, but at least 3G and above.

Please see my earlier post. You may have a 4G SIM card, but the mobile network setting on the phone cannot be put to 2G while you're in Singapore due to the recent shut-down.

Singapore has no 2G network anymore, same for other countries like Australia and IIRC, Taiwan sometime in July.

What phone are you using?

I bought a Samsung Galaxy A5 2017 recently, and can confirm that I can activate both SIM cards simultaneously after a firmware update. One card is on LTE/3G/2G (auto connect), while the other one is on 3G/2G (auto connect) - SIM 1 is using 4G while SIM 2 using 3G.

You won't be able to get a connection if you set mobile network to 2G only.

I'm further away from the causeway, a couple of days before the deadline already my old dual SIM phone became like single SIM.

I think XR Note4 lets you use 3G on both slots, no sure... but with the older phones you'll have to choose which one you want to turn off.

If you need to visit Singapore frequently and plan to buy a new phone, you'll have to be careful what phone you choose. I think not all new phones can support the use of 3G on both slots, or 4G on one and 3G on the other.

Yes, Maxis' roaming partner is Singtel but regardless, any Singapore network you put to 2G will not get a connection anymore...

Referring to dual-SIM phones, not all can support 3GDS or 4G/3G. So when you set one SIM slot to 4G or 3G, the other slot will automatically go to 2G.