MT discover

hello guys;
i have 2 MT 2.9.27 connecting together localy MT1 and MT2, MT1 is a gateway and dns server for MT2.
i have the discover option on MT1 enabled and working good but when i enable the discover option on MT2 to use packing between MT1 and MT2 local interface stop responding until i restart MT2 and disable the discovery option and disable enable the local interface. any ideas.

best regards