We have this scenario, (click on image to view in wide)
we have connected the switch and the routers with the with S+DA0003 - SFP DACs (https://mikrotik.com/product/SplusDA0003), the switch only have 4 bridges with 3 interface in each one, all is configured by default, no networks or firewall or nating rules and basically is working a a simple switch with this 4 bridges, nothing more.
all ISP have 1Gbps symmetric links.
when we make a speed test of this setup, the D/U speed is not over than 300Mbps, ever. Now, if we connect directly the ONT of the ISP to the routers the speed of D/U is 1Gbps, ever.
this is a hardware limitation or a misconfiguration? we can not understand why the performance is too poor if is working like a switch/bridge.
Ros: 6.44.3
Switch model: CRS328-4C-20S-4S+RM
Routers model: CCR1036-12G-4S
UPDATE: fixed image url