You must be sure before go to immigration that hotel registred you online because it s seems to have some problem for loading and certificat of hotel isn t enough .

Hi! I came back in thailand by phuket sandbox 7 august (my oa 1year extension was valid untill 31 august . Living in chiang mai and with the poor offer of flights for return ,i made extension at phuket ,needed same requirement that CM ,but needed adress in phuket (hotel certificat ,and register on immigration online .Gave passeport and documents friday and picked up monday without problem.Arrived at CM ,i went immigration and changed adress .