I recently had 2.5gbps symetrical fiber installed it came with a cheap tplink ex820v which when all connected provides 2.5gbps download and 2.5gbps upload no problem at all.


i had this setup :


ONT cat6 cable to ex820v 2.5g wan port  then cat6 cable from 2.5g lan port to a 10 gbps network card 
speed test 2.5g up and down consistent

i had an issue with that cheap router and the customisaton of firewall rules so i got myself an ER8411

i added two H!Fiber 10gBase-T SFP+ to rj45 tranceivers into the first and second SFP + porns on the ER8411

i setup the second sfp Port as the only port on the default vlan and connected my pc too it, in exactly the same configuration as before - just pulled the cat6 from the wan port of old router into sfp wan port of the ER8411 and the cat6 from my PC to the second SFP port. 


then i do speed tests - i can get 2.2gb download which is a bit slower but i can live with but the upload caps out at 1.2gb it never gets any higher. 

any ideas what could be causing this?