Likely finicky, they're explicitly not supporting it, and posts here seem nervous about it: https://forum.fairphone.com/t/general-fairphone-3-discussion...
Well that's not too bad. I could live with 3G personally, given what I use my phone for, but I doubt many others could.
https://support.fairphone.com/hc/en-us/articles/360032577632...
https://support.fairphone.com/hc/en-us/articles/115001535686...