Cannot ping from Pepwave BR1 to client PC


I have a simple connection as per below:

Pepwave BR1 (LAN1 port) --> Unmanaged Switch --> Desktop

I managed to ping Pepwave BR1 from Desktop but not from Pepwave BR1 to Desktop. But when I changed the unmanaged switch to any managed switch (using Juniper EX3000 series), ping was successful from both ways Desktop and Pepwave BR1. Any ideas why this is happening? Please advise, thanks.