I cannot confirm this so far. I have several Shelly and Switchbot devices in the network.

The low speed may be due to the fact that the Ubiquiti U7 Lite only has a 1 Gbit/s LAN port - more is not physically possible. If your Wi-Fi throughput is still only around 200 Mbps, this may be due to a connection to the wrong frequency band (e.g. 2.4 GHz), interference or an unsupported Wi-Fi standard on your end device. If these points have been checked and the problem persists, please contact Ubiquiti Support for further assistance.

I think it is due to the cable being too long or too old. A Cat 6 or 7 should provide a permanent remedy. I have both in operation without any problems. But if tested, switch to manual in the switch and set 2.5gb.

Hello, only works with PoE. This means that you must have a PoE switch or a PoE injector. (https://www.digitec.ch/de/s1/product/ubiquiti-25g-poe-adapter-8023at-poe-30-w-poe-injector-54802790)

The number of access points (APs) that can be combined for a mesh WiFi is not directly limited as long as the infrastructure and network management support it. However, to realise a mesh network without additional costs, you need a UniFi Network Server to configure and manage the APs. This server makes it possible to efficiently manage multiple APs and create a coherent mesh network.

The U7 Lite does not include a POE injector. This is confirmed by third-party retailers and product listings, which explicitly state the injector is sold separately. While the in-house data specifies 802.3af PoE compatibility, it does not mention included accessories. For official confirmation, consult Ubiquiti's product documentation or support channels.