I had exactly the same experience. As a matter of fact, the TP-Link began to interfere with DHCP and shut down my intranet. I let this happen a couple of times to be sure it was reproducible. The issue seems to be that the TP-Link draws a lot of power, maybe more than spec. I called TP-Link and a woman who sounded about 16 years old walked me through a flow chart that ended in having me cut the transmit power and retest. Voila. Cutting the transmit power solved the problem, unfortunately cutting the transmit power in my situation, defeated the purpose of using the TP-Link. In the end, I ran an Ethernet cable to the opensprinkler and returned the TP-Link to Rayshobby.
Can you cut the transmit power and retest? It would be helpful to confirm my results.