Hello   @c300g97 

Thank you for reaching out to us, I'd recommend checking if power line device work better on current firmware or not, you could keep using the firmware if it works better. 

Otherwide, try to downgrade to TL-PA411 V2 firmware, if firmware can't be downgraded,  as this model is a pretty old, you might also consider purchase /upgrade a new AV600 powerline device/kit like TL-PA4010. 

Kindly note that Hardware version could not be upgraded or downgrade, and device need to use firmware according to its hardware version country version has a chance of damaging the device.