At default, Jun''s 1.03b doesn't have Broadcom NIC driver. -> It can find by Synology Assistant at first, later your N54L never response.
If you want use default NIC, may need extra.lzma which contain Broadcom NIC driver.
No want use extra.lzma, buy Intel PCIe Gigabit NIC and install on N54L, and in BIOS you must disable Internal NIC.