A Lotus Notes client on a Windows NT or Windows 95 computer using NetBIOS and NWLink on Token Ring may fail to connect to a Lotus Notes server on Ethernet. This symptom can also occur when a Notes client is on a FDDI ring. The network adapter on one side of the conversation is on a link that has a larger frame size than the link on the other side, and IPX does not do fragmentation. According to the IPX specification, it is up to a higher level to determine the maximum transmit unit (MTU). For NetBIOS traffic over IPX there is no MTU negotiation scheme. To work around this problem, decrease the frame size of the Token Ring network adapter to 1,012 bytes on the Windows NT computer.

Hive: HKEY_LOCAL_MACHINE
Key: SYSTEM\CURRENTCONTROLSET\SERVICES\NWRDR\PARAMETERS
Name: DefaultMaxPacketSize
Type: REG_DWORD
Value: 1012 decimal radix