we deprecated "client mode" because we changed the design to run MQ connections over WireGuard, which required a constant server connection over WG, making the server client mandatory. However, in 0.13 we switched to using server-generated certs instead, so technically we could remove this requirement. However, it's still worth thinking about, because UDP Hole Punching currently works using WireGuard. If client mode is off, udp hole punching will not work. This may be fine for some use cases, but it also makes it a lot harder for us to track edge cases with a small team. So Tl;DR we could make client mode work again, it just requires more work and we haven't seen a whole lot of demand to get rid of it yet.