At country A, Customer B using RTN900V001R003.
U2000 can’t Login NEs due to large number of NEs under one Gateway NE (GNE).
The management is interrupt, GNE can’t Login.
From Main topology check the Link between 2 subnet using U2000.
Disable the DCN management on IF board.
How to disable DCN management on IF board?
From the Object Tree in the NE Explorer > choose Communication > DCN Management.
Select Port Settings in the Physical Inventory window.
Choose the IF, at Enable statues change to (Disabled).
Repeat steps at NE2, to disconnect the management.
Actually every GNE supervise less than 100 NEs, but there is a Link between GNEs, so in this case the GNE accumulate the number of NEs under GNE supervision.
According to sketch, can supervise NE1 through GNE1 or GNE2 through link.
should be disconnecting management at Link between NE1 and NE2.
Check the number of NEs under GNE, if there any link between GNEs, can consider this when do management plan or disconnect the management of this link.