that zte mf93d is really suck... or maybe i can say, all zte is like that, im using that modem right now, same problem as you, disconnect and it wont auto connect back, i try with other telco, also when it disconnect... u wait forever to make it auto connect. but at least, when with celcom, clicking connect at modem page will re-connect the internet. maxis is worst, when disconnection happen, click connect will always get "failure"... no other option, need to restart.
same with wifi, sometime wifi not detected and need to restart...
maybe after hari raya i will consider new (huawei) lte modem...