Not much to go on, but perhaps someone knows your Wi-Fi password?
Another thing I’ve seen at my ISP’s support forum is that some customers have MoCA enabled on their gateway (possibly delivered to them that way) and yet don’t have a MoCA filter on their incoming line. This causes leakage between their LAN and a neighbor’s LAN who also has MoCA. This can be extremely confusing. (This applies to cable ISPs.)