@FrancoXa 

Hi, since TL-WN725N is 2.4ghz only that is easily interrupted by other wireless signals on the same spectrum, if possible, it is suggested to change the wireless channel on the main router to channel 1/6/11. the orientation of the adapter also matters since it is a nano adapter. Please try to face it directly to the main router, and try to move it away from the metal or concrete shields.

Please also install the driver here to see whether it helped improve the speed:

https://static.tp-link.com/2019/201911/20191129/TL-WN725Nv3.zip

 It is also suggested to check the current wireless signal strength via wifi analyzer Apps or other similar APPs, and the current wireless link speed on the computer:

How to check the associated/link speed on a wireless client

For more advice, please refer to this link:How to improve the speed of TP-Link wireless adapters

Thank you very much.

Best regards.