QNAP TS-669L(QTS 4.3.4), ZT, node online but unpingable

Hi everyone, I got the ZT (https://github.com/iranee/qnap-zerotier) installed on my QNAP TS-669L(with the latest QTS supported in this model), The whole situation is almost same as what discribed in https://discuss.zerotier.com/t/qnap-ts-231-with-zt-1-10-1-is-connected-but-not-pingable/9862. Checked with zerotier-cli, the node is online and active, but it is unreachable by all the other nodes in the virtual network. the snapshot for checking peers is shown here.
Really appreciate your help, thanks in advance.