Can a student on an ED visa travel outside Thailand and return without issues?

A friend with an ED visa can travel abroad and return to Thailand, but they must obtain a re-entry permit from Immigration to avoid losing their visa. For trips up to 7 days, there are generally no issues. For trips up to 14 days, a valid reason must be provided, as holidays are not considered valid. If the absence exceeds 15 days, the visa may be at risk of cancellation. At re-entry, the immigration officers may ask questions regarding the trip and the student's status.