Good day,
I own this device, but I have never used it together with a switch, let alone with W-Lan and Lan together. Theoretically it should be possible, since a repeater has to manage all clients via W-Lan anyway, it also has to assign an IP to any client via DHCP. In my opinion, the firmware should not cause any problems. However, this problem is not mentioned in the manual, which in turn may mean that the firmware was deliberately saved in order not to compete with other products.

But I have attached the link to the manual. Maybe you interpret it differently.
http://static.tp-link.com/TL-WA850RE...

Ps.: The part is well worth the money, I have never had any problems with it.