LTE download speed less than 300kbps next to the antenne

Hi sorry for my question in english but im facing a major lack of download speed on my LTE connection. this is now happening since few weeks and is annoying me as i dont have internet at home and fully rely on the O2 LTE.

here are some facts and hope you can help:-

• still have 20GB of data left for this month
• im 300m close to the antenna so full signal
• im outside standing next to the antenna
• i checked the O2 website to see if there are any faults in my antenne and it says none
• when i run a speed test via the O2 app i get download speed of 300kbp and upload between 4mbps and 8 mbps.

pls help