I cancelled broadband 4 years ago and have been using AIS ,DTAC and NT sims in my phone and they have been very reliable and as a bonus you don't need to go looking for wifi hotspots when away from home.
I have also used a sim router with the same success for 4 devices at home,but now have 2 phones 2 sim cards , home devices ,TV,laptop,2nd phone and PC connect to hotspot on my phone,no problem.
AIS sim 15mbps 70gbpm
DTAC 30mbps unlimited data
NT Thunder UpTo 30mbps at my home unlimited data