@MoreConfused That's correct. Another option that you could use is the C80 AP mode (Case 1) but that involves additional cabling (if applicable).

@MoreConfused I really don't know the answer to this question but earlier in the same thread there's another post which offers a possible justification.

@Luca5chv Can you post a screenshot of your TL-WA850RE LAN configuration ? Any DHCP address reservation or IP&MAC binding configured on your router ?

@Yorocoboy Try to power the WA1201 with its 12V/1.5A original power adapter (not the passive PoE) and check if there's any difference.

@Al22_9 Your TD-W9960 and TL-WA854RE configurations seems fine. According to the screenshots the only DHCP server in your network is on TD-W9960. For easier access to the TL-WA854RE WebGUI I would...

@Yamshanks It's highly likely that the ISP customized your router firmware and set a custom administrator password. Try the solution posted here and check if that works for you.