> Gembird NIC-GX1 with Realtek 8111C :-(
> is there any chance it will work with MorphOS ?

There have been some mentions that RTL8111 GbE controller works:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=11137&start=764 (#765)
https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=12716&start=39 (#40)

...and even some mentions of your exact card:

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=12413&start=13 (#14)
https://morph.zone/modules/newbb_plus/viewtopic.php?forum=11&topic_id=13050&start=8 (#9)