I ran into an issue recently that I'm trying to understand. I'm connecting to a Raspberry Pi through a LAN7500 USB2.0 to 10/100/1000 Gigabit controller under three situations.
A) From the LAN7500 directly to a AX50 router
B) From the LAN7500 to a TL-SG105[V2] gigabit desktop switch to an AX50 router
C) From the LAN7500 directly to a TL-WR802N access point [10/100Mbps]
In situations A and C, the connection is established immediately, at 1000Mbps and 100Mbps, respectively. In case B, the connection is exceptionally flakey, or just won't connect at all unless I manually configure the interface speed to 100Mbps.
Network Engineering is out of my wheelhouse, but I'm curious what's causing this lousy connection. Is the switch too old and not complying with some new ethernet standard, or is the added routing between the router and LAN7500 through the switch adding excessive overhead to the TCP packet that LAN7500 can't keep up with? The third explanation is that the firmware to the LAN7500 is incorrect; I'm less convinced of this, since there are no issues are connecting directly to the routers.
I'm honestly still trying to figure out how the USB2 protocol can deliver 1000Mbps ethernet, given its maximum bandwidth is 480Mbps.
