Thank you for the post. As this is an onboard NIC On Ggiabyte board, have you tried check if they have newer driver version that could be of help. You may also try the Intel driver from our website but we cannot guarantee 100% compatibility
Please ensure the switch has the same configuration when you tried manually set Duplex & Speed to 100mbps or in auto-negotiation mode.
Try to adjust the flow control setting in the advance tab of the network adapter to see if this will make any difference.
Good day. Please feel free to update me if you have tried the suggestion or you may contact Gigabyte the board manufacturer for support in case you have not done that. As this is an onboard NIC, it is recommend to use customized driver from the board vendor. Here is the website regarding OEM NIC support
I've found out that the problem was in incorrect connection of the in-wall
cable to the LAN socket. After rewiring, the problem disappeared.