An issue was discovered in OpenWrt libuci (aka Library for the Unified Configuration Interface) before 15.05.1 as used on Motorola CX2L MWR04L 1.01 and C1 MWR03 1.01 devices. /tmp/.uci/network locking is mishandled after reception of a long SetWanSettings command, leading to a device hang.
https://lists.openwrt.org/pipermail/openwrt-devel/2019-November/025453.html
https://lists.infradead.org/pipermail/openwrt-devel/2019-November/019736.html