RSSDP is a 100% .Net implementation of the Simple Service Discovery (SSDP) protocol that is part of the Universal Plug and Play (UPnP) standard. SSDP allows you to discover devices and services on a ...
It's not a matter of timing. WiFi.localIP () always return 0.0.0.0 instead of the real IP and therefore I assume, ESPHome somehow uses a different function/stack to get its communication running, ...