the problem could be too much power.
4 x 1W cards inside a box…
use one radio in one box (metallic), use short cables from box to antenna (max 1m), use radio with max 23dbm, use sectors with more gain (60°, 17dbi). And a good pigtail ufl-NF.
Use nstream! (ops you have nanostation).
You coud try a box with rb411ah + R52 a+ 1meter NM-NM LMR400 + 60° MTI (see http://www.mtiwe.com/uploads/product/230.pdf)
you can test if this is better than your setup.