What actually fails
Video calls go first. They are the most sensitive thing you will try to do and the first to break when a hall fills up.
Then the ride app, at the worst time, which is when everybody leaves at once.
What to do about it
Install the eSIM at home on Wi-Fi before you fly, and leave the line switched off until you land.
Days on these plans are calendar days in Thailand, not 24 hour blocks, so a line switched on at 11pm has already spent that day. Switch it on in the morning of the first day you need it.
The two conference days are the ones that matter, but the side events either side are where the meetings get made, and those run on your phone.
