GS110EMX: 10G ports throttle uploads to 250-300 Mbps

For my issue, I already had both switches in house. It was the unknown operation and configuration and assuming that the ports would work in the initial any configuration and failed.  The host routers port was going to the SFP port on the XS switch, then from here, 10Gb ethernet port was doing down to the MX 10 Gb port. Apple TV was connected on the 1Gb port on the MX switch. After someone said there was a problem after using the Apple TV streaming that was connected at the MX switch. Found all devices on this segment with out IP addresses or internet services. Any streaming on the ATV would cause this network segment to fail entirely. After troubleshooting then swapping around were the host router connected and using the SFP port on the XS switch for the uplink to the MX switch to it's 10Gb port. Problem solved. Zero issues since. 

I also use these switches for Orbi system ethernet backhaul connections when needed. All that works too. 

Seems that NG has these partcular switch ports used for specific uplink configurations and not for any general use. So you may need something upsteam for more geneal port usage if you need better port operations. The XS505M is solid and works well. All it's ethernet ports are up to 10Gb supporting. I added the SFP adapter to add one more 10Gb port that I needed. And I see it also mentions the SFP port being the uplink or core backbone so kinda makes sense that it works correctly with the MX switch on it's 10Gb port.