I have an Ethernet Loopback Plug (4 Pairs) made and trying to test the Gigabit Interface on a 3845 Router with a fail result. The interface will show up/up only if I set the interface to 100M/Full Duplex when I plug-in the Ethernet Loopback Plug (4 Pairs). I don't see this Gigabit Interface @ 3845 router has any option to set it to internal or external loopback. Any help will be appreciated, thx.
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