I love WFH but there is no denying it has a learning curve. Those who have adopted it fastest are those who already have skill communicating remotely: IT, gamers, amateur radio, some other hobby groups. Those who are struggling are often just untrained communicators. Don’t focus on training to them to work remotely so much as focusing on how to communicate as part of a team. I would start with asking them to check in once a day around a mutually agreed time just to say whether they’re doing alright or being blocked by something. Anything that opens the door will get people talking more regularly.