All my stream connections run at 1.0Gbps at full duplex. There is no switching from 100Mbps from one session to 1000Mbps in another session like what is happening on your computer. OBS Studio determines speed of the network adapter by querying Windows at the time of RTMP connection and shows this message:
23:10:59.983: [rtmp stream: 'adv_stream'] Connecting to RTMP URL rtmp://live-mia.twitch.tv/app...
23:11:00.007: [rtmp stream: 'adv_stream'] Interface: Realtek PCIe GbE Family Controller (ethernet, 1000 mbps)
23:11:00.956: [rtmp stream: 'adv_stream'] Connection to rtmp://live-mia.twitch.tv/app successful
Since your ethernet adapter is changing oddly from two different speeds, something is not right in your network. If you go to your network driver adapter and look at its speed and duplex setting, it is likely set to Auto Negotiation by default. This means the adapter is negotiating with other devices on the network at an agreed upon capability. If you set it to a fixed value (like 1.0Gpbs Full duplex), you are telling every device it communicates with that this is the only speed and duplex it will communicate with.
With Auto negotiation on, it is either your network adapter, the other device on the network that is running at a slower 100Mbps, or a middleman like a router/switch running at a slower speed. It could also be that there are devices on the networking producing so much network bandwidth that it can only operate at 100Mbps.
- Check to see if there are other devices on your local area network that are using the network. This includes all desktops, laptops, Wifi devices, smartphones. Everything.
- Make sure that when you stream, nobody else in the house is using the network. If dad is watching Netflix while you are streaming, well, that is not a good time to stream. If your brother is downloading files off the Internet, that isn't good either.
- Check the Ethernet cable for damage and see if:
- RJ-45 plastic jacks are damaged
- RJ-45 ports on the motherboard or cable modem/router/switches are damaged
- The cable itself has been damaged
- Cable is lying near strong magnetic interference like flourescent lights, microwave or speakers
When in doubt, just go buy another Cat 6 cable.
Lastly, go to your motherboard manufacturer website and update with the current network drivers. Don't use the Realtek driver from the Realtek website. Only use the motherboard manufacturer's implementation.
2:45:48.178: [rtmp stream: 'adv_stream'] Interface: Realtek PCIe GbE Family Controller (ethernet, 100 mbps)