The range will also depend on the antenna used. From the data on that Nano it uses the u-blox NINA module with its own antenna. Knowing u-blox I would have though the antenna would be reasonably good. Is there also a separate antenna pin on the Nano board?
Have a look at the NINA documentation at NINA-B1 series (open CPU) to see how to enable long range mode.
Hmm, yes. I have one of these modules waiting to be used in my current project so I just had a look at it - I don't think the designers of the board have entirely followed the u-blox recommendations in the product intergration manual here: https://content.u-blox.com/sites/default/files/NINA-B3_SIM_UBX-17056748.pdf - see pps 38-39. For example there should be at least 10mm of ground plane either side of the antenna, so the board would have to be 10mm wider than it is. How do you have the module mounted? There are also some recommendations about that which could help.
Check the antenna area for missing components. They are easy to rip off and have been causing short range issues for a few users.
Test your Arduino with your smart phone. You should be able to keep an active connection for many meters. Just connect with a generic BLE app and then walk slowly away.
Here is a link to a post from a long time ago with some tests I did reply #9 and a picture of the antenna area reply #18.
Well your mobile phone is a lot more expensive. So, hopefully engineers spend some more time and effort on the antenna design to make BLE work even better.
