I recently noticed a problem that, when ONT, the Huawei EchoLife HG8110, HG8120 and HG8120R watched the Ethernet ports shutdown about 30 seconds after the ONT was turned on.
At the same time, ONT continued to work, the optical connection did not disappear.
On the Huawei EchoLife HG8110 the link did not disappear, but the interface ONT 192.168.100.1 stopped pinging.
The cause was defective power supplies.