interference electromagnetic emi rf

Hello all I've had my MavicPro for just shy of a year. I live in an apartment complex which does have rather heavy wifi interference Ill admit. Lately tho it seems I a having issue with lagging between the MP and my iPad mini 2. I have flown here many times in Dif conditions of temps and weather...

I'm in Heidelberg Germany on vacation and have been trying to get some flight time in. Several times, in different parts of town I've gotten the a warning indicating 'Strong magnetic interference which could cause RC control issues' (or something similar, not verbatim) This warning has occurred...