Thanks for the results.
Please do not share your customer number, but the UID number you received from Speedtest. For security reasons you should never share your customer number publicly.
To the results:
You have a 300 subscription and get an average of 287 Mbps. This corresponds to a normal value and is also reflected in the good signal values.
However, since you only have a 100 Mbit network card in use, you are limited in speed. With a Gigabit network card and an ac Wlan standard capable Wlan card, this would look even better.
So I can tell you with confidence that the symptoms in your case are local and come from your devices.
With the receivers for Wlan it is not only important that you are connected to 5GHz, but also that these devices support the Wlan standard ac. This is the only way to achieve the desired values. Whereby 250 is already very good for Wlan.
I am glad that you found a MAC and saw that the Speed is fine 😉 Enjoy it.
I hope that I could help you.
Best regards,
Ahmet