@mshulman In the document https://static.tp-link.com/upload/manual/2024/202407/20240715/7106511303_Tapo%20S515(US)1.6_QIG_V1.pdf I see: Q1: Can I connect two Tapo smart light switches to my 3-way or...

@Carl I was just told by tapo tech support that I could use the S515 3 way switch with a 4 way circuit, but only by using a single smart switch with 2 mechanical switches....