Hi, first time post!!

I've just purchased the Deco X50-5G AX3000 and an Unlimited EE SIM card as my copper line only gives me download of 20Mbps. The Deco is great, 40-50 latency with downloads of 90-100Mbps. But I'm hoping to improve and stablise these figures by installed an external antenna - so my question is which one?! I'm not technical enough to understand the frequencies and bands so I've found some antenna's that say "all bands" so will they work? Has anyone done this already?
thank you

darren