Sonoff ZBBridge WiFI bridge from Itead is not a robust solution with ZHA because the protocol it uses.
Read zigpy devs warning here: https://github.com/zigpy/bellows#warning-about-zigbee-to-wifi-bridges
Basically the serial protocol API for EmberZNet Zigbee coordinator application running on the Silicon Labs SoC/MCU does not deal well with unexpected loss of communication caused by network drops. The reason Ember remote bridges over serial-to-IP proxy server is not recommended is that clients using the EZSP serial protocol requires a robust connection between the EmberZNet Zigbee stack running on EFR32 MCU and the serial port of the Zigbee radio. With solutions such as ITEAD Sonoff ZBBridge or a Ser2Net serial proxy connection over a WiFi network it is expected to see NCP entered failed state. Requesting APP controller restart in the logs. This is a normal part of the operation and indicates there was a drop in communication which caused packet loss to occurred between the zigpy radio library and the Zigbee radio. The use of serial network proxies/bridges/servers over WiFi is therefore not recommended when wanting a stable Zigbee environment with Silicon Labs Ember based Zigbee radios. The developers of the bellows radio library for the zigpy project has more information about this if needed.
Ember USB Zigbee adapters/dongles/sticks (like this) are highly recommended over using a remotely network connected Ember module using a serial-to-ip bridge / serial forwarding server like ser2net.
PS: Recommendation is to use a USB extension cable with any USB radio adapter (Zigbee, Bluetooth, other RF or WiFi) just in order to get them away a little from possible signal interference if nothing else.