Something happened...
Indeed, the second connected network PCI card was incompatible. So I plugged another PCI compatible adapter with chipset RTL-8139C and after turn power off the serwer and reloading DSS console I just saw the both network adapters in DSS console: 1. the lost earlier adapter onboard RTL-8111DL (found itself, also I see the driver of adapter, now) and 2. the second network adapter I just connected. Then I had to recover data on the storage disk by upload and restore saved settings. Now working normal.
I still have one problem I wrote the above: I can not upload in webGUI (Maintenance - software update) any System software update (any build) I downloaded to the PC from website open-e.com. How I can do it? I do not want install. Newest build I can loading is b5845 (I can not loading next b6335,b7337-black screen with "Loading..."), but DSS download only b7337 by update downloader. So, I want upload b5845 from my PC (in LAN) by webGUI because I do not want use the installer (with romove all system data from disk).