The compatibility of the TP-Link TL-WA850RE with the Connect Box 3 Ethernet from Sunrise depends on the network protocols and the configuration. The TL-WA850RE supports the IEEE 802.11b, 802.11g and 802.11n standards, which makes it compatible with most WLAN routers. However, there is no specific information on whether it works specifically with the Connect Box 3 from Sunrise. It is advisable to check the network protocols and configuration settings to ensure that both devices work together correctly.