What is the ruling on the prayer of congregants in the basement of a mosque if the voice of the Imam is cut off from them and then returns?

If the sound is cut off from the congregants who cannot see the Imam, they have two options: it is preferable that one of them steps forward to lead them in prayer as an Imam, or they can intend to separate from the Imam and pray individually. The evidence for the permissibility of separating from the Imam is narrated by Jabir concerning the story of Mu'adh, who used to pray with the Prophet (peace be upon him) and then return to lead his people in prayer. One time he prolonged the prayer, so a man prayed alone.