Problem with advertised speed on ethernet interface

RouterOS General
1

Hi to all!
I have the following problem:

The network diagram:
[ISP Router]------------[MKTK Router]----------------[PC]

  • ISP Router configured as a modem(bridge). Port speed: 1Gbps.
  • MKTK Router(951G-2HnD)has a configured bridge.
  • PC has 1Gbps NIC.

The problem:

  • When PC is directly connected to ths ISPs router the NIC speed on the PC is 1Gbps.
  • When PC is connected to the MKTK Router the speed of the NIC drops to 100Mbps.
  • When I tried to advertise only 1000M(half and full) the interface didn’t worked anymore.
  • When I unchecked the Auto Negotiation and checked 1Gbps and Full Duplex the ethernet interface didn’t worked anymore.
    I had to connect to another interface to enable 100Mbps(full) on the interface in order to make it work again.
    Tested with the same cat5e cables on different ports on MKTK Router.

Print screens:
Before:
mktk00.png
and
After:
mktk01.png
).

Can someone tell me why I can’t connect from the PC to the MKTK Router at 1Gbps even if the router advertise 1000M(half and full) and why when the speed settings are changed in the MKTK Router the interface doesn’t work anymore?

Thank you for your answers.