I would use 'one' in this case.
User x has disconnected. One has 5 minutes to reconnect.
In Dutch we have the third person singular neutral pronoun 'men'. It is quite formal language and most of the times only used in written language. A lot of people dislike it (not me) and will use 'je' (= you singular), 'we' (= us), 'ze' (=they) or 'hun' (=their) instead. I translate 'men' preferrably with one or you singular. I did not know that 'they' was possible, but just as I would not use it in Dutch for a singular pronoun, would I not think about it to use it in English.
It might be interesting to tell that 'ze' is ideally used when the listener and the speaker are both not involved. That is clearly the case in this message from chess.com. It is the third person, who is the subject of the sentence.
It puts the lotion in the basket!