@Ek9max Do you mean after you upgrade to the latest firmware, the download speed becomes slow? Now for the EAP245 V3.0, the latest firmware is Build 2.3.0 20190731, are you using this firmware? 

Here are some suggestions for your slow speed issue. 

1. Please modify the Tx Power of the EAP devices. What's the distance of your EAP devices? If they are close, please try to change the Tx power to reduce the interfere. 

2. Please try to disable Band Steering, Load Balance, Airtime Fairness and have a try. 

3. Please change the channel and channel width to have a try.

@Ek9max 

I am experiancing the same issue with the new OS but not sure if it's the AP OS or omada controller as updated both. My download speed comes around 160 to 190 where as upload speed 380 to 400+ I tried played around with few settings but no luck then I gave up as I know it will get fixed whenever the new firmware comes up which would be 6 months if I look at the past history like around May/20 time frame but I am hoping they would release it earlier with bug fixes and add some of the features/enhancement that people arerequesting in the forums. Figers crossed.

@wifiprosz Do you mean that after you upgrade the Omada Controller and the firmware of EAP, the wireless speed becomes slow? 

What's the model of your EAP? Your firmware is the latest version, yes? Please modify the Tx power of the EAP to have a try.