Skip 20F001N in RTL8019AS

Um, no... I seriously doubt this would work. There are several inductors and a transformer in the block for filtering and isolation. And depending on the controller, the transformer windings are also not

Why not just get an RJ45 jack with internal magnetics? They're only slightly larger than a standard RJ-45 jack, and not expensive at all. Then only a few resistors and caps are needed on the signals between the RTL8019AS and the RJ-45.

Bothhand and Delta are very popular, but there are many companies in this space. Here are a few:

Digi-Key sells Tyco and 1-2 others, though they're cleverly hidden amongst the other RJ-45 jacks and critical specs are missing (i.e., read the manufacturer specs before looking on Digi-Key for pricing).

See also

I have tried connecting it directly to PC and XP could detects the existence and shows the connecion icon on the tray. But I am not sure whether this represents the data sent/received is ok. But anyway, your information is very helpful. Thank you very much.

OK, now I use a T-filter which is from an old broad. The data can be received now. So I confirm that direct connection is not ok.