Outside WIFI shielding questions

Hi, I have severe ME/EHS/MCS. About a fortnight ago, I noticed that a worsening of my symptoms, including insomnia, had coincided with the re-opening of the caravan park next door to me. The deterioration felt radiation induced and enquiries led me to discover that the caravan park has wifi and "strengthened their hotspots over the winter"!!
I have not been able to measure with a metre but their wifi signal can be picked up with a mobile phone in the majority of the garden (with a strength of two dots out of three) and in my home.
Have you effectively shielded an outside area against wifi? Is there a particular type of shielding fencing available? Could outside shielding paint be painted onto a fence or wall? Would building a wall or planting lots of trees make a difference?  Have you tried mesh on trellis?
Basically, what have you used outside which has protected you from EMR and where is the best place to look online for this information?
Thank you very much