Try temporary disabling other 3 NICs to check if that's the problem.
"A common mistake that people make when trying to design something completely
foolproof is to underestimate the ingenuity of complete fools" - Douglas Adams
Did disabled otther NIC's but it couldn't help me. Another interesting thing I noticed here is that eventhough tnsping takes > 800ms at first time then the subsequent tnsping takes only <100 ms, Why??