I have noticed unusual thing about bandwith test.
I have 3 Mikrotik's router.

MTK 1 (v 2.9.27)
MTK 2 (v 3.9)
MTK 3 (v 2.9.27)

Test is performing from MTK1 and MTK2 to MTK3.
From MTK2 to MTK3 RX is almost two times smaller then TX.
Test was repeated many times in a diffrent time.

From MTK3 to MTK2, reverse case, RX is two times bigger then TX

From test MTK3 to MTK1, RX is equal or approximatly equal to TX


Can somebody explain me why is this happening ?

You haven't provided enough information about your hardware setup and enviroment...

Maybe you first upgrade the 2 systems with 2.9.27 to an actuall version.

Regards
Lutz

Thats hard because he must pay.

upgrade from 2.9.27 to 2.9.51 is free =)

It's only free if you have a legal license to start. Chances are anyone who is still using 2.9.27 is not using a legal license.

you don't need to point to it every time you see '.27'