Any ideas? ROS 5.9, Nstreme, best fit 3999
I Upgrade it to 5.14 + new boot, We wil see...

Routeros version and bootloader has absolutely nothing to do with 'extensive data loss'. At least in my experience. It's entirely mechanical or rf related problem. Try changing channel, polarization, checking signal levels. Do a spectral scan and freq usage scan to check for less congested channel. Keep as further as possible away from channels that are populated with devices showing high signal levels in your scan. Try enabling ANI. Read previous forum posts. Extensive data loss is probably the most abundant topic since beginning.