While universities closed, implementing remote teaching and learning in response to COVID-19, this change significantly impacted the lives of graduate students, given their exposure to unique and diverse experiences. It thus has become essential to understand the possible differences in regard to the pandemic's impact on international and domestic students. The aim of this study was to explore the consequences of the challenges posed by COVID-19 on doctoral students' wellbeing in Russia. The study surveyed 4454 doctoral students across 249 Russian public universities. The challenges posed by COVID-19 negatively affected international doctoral students' learning experience (β= -0.269, p<0.001); students' satisfaction with supervision (β= -0.098, p<0.001); dissertation experience (β= -0.039, p<0.001); and doctoral program satisfaction (β= -0.034, p<0.001). Furthermore, the challenges posed by COVID-19 affected domestic doctoral students' learning experience (β=-0.368, p<0.001); students' satisfaction with supervision (β=-0.194, p<0.001) and doctoral program satisfaction (β=-0.034, p<0.001). However, the influence of the challenges posed by COVID-19 on communication frequency was relatively positive for both international (β=0.060, p<0.001) and domestic students (β=0.021, p<0.001), and dissertation experience (β=0.061, p<0.001) was also positive for only domestic students. Furthermore, controlled factors comprising field of study (β=-0.033, p<0.001); year of study (β=0.127, p<0.001); and university region (β=-0.056, p<0.001) influenced the effect of the challenges posed by COVID-19 on international doctoral students. The COVID-19 challenges had the greatest impact on the wellbeing of international students. Furthermore, both international and domestic students' communication frequency with their supervisors underwent a relatively positive impact (which implies no effect on both categories of students). Furthermore, the challenges posed by COVID-19 had no effect on domestic students' dissertation experiences. Finally, among the controlled variables, field of study, year of study, and university region were discovered to be significant factors in relation to the challenges posed by COVID-19 for international students.