The outbreak of COVID-19 more than before accelerated the prevalence of online instruction. Now the time has come to assert that online teaching is not restricted to the lockdown times, and rather is a useful way of teaching or learning which might help teachers and students in different conditions. The current study attempted at exploring the challenges of online instruction faced by Iranian EFL teachers who worked in public schools. To this aim, the researcher used a mixed-method research. To collect the data, 90 EFL teachers participated in the quantitative part and answered the Technology Implementation Questionnaire. Additionally, 12 EFL teachers responded to 12 interview questions. First, the values, expectations and costs Iranian EFL teachers associate with the implementation of computer technologies in English instruction were recognized. Then, it was investigated if the factors related to school environment, demographics and computer accessibility affect Iranian EFL teachers' beliefs towards technology implementation. Then, the main obstacles hindering the process of online teaching and technology integration in English instruction in Iranian public schools were explored. These obstacles included general obstacles like the speed of internet and obstacles specific to Shad application, like the problems related to data transfer and synchronization. Finally, solutions and/or recommendations for enhancing the effectiveness and advancement of online education in Iran were offered. This study has implications for developers of national educational applications and the government officials, especially the officials in the Ministry of Education.
