you can and should write about every that case to support@mikrotik.com - they can do change and discovery why that this happens.
All LTE devices are warranty fix via MikroTik directly and give that wrong cart to warranty. They should be stable.
I remember old post about the waterproof of sxtr.. http://forum.mikrotik.com/t/sxt-are-not-for-outdoor-damaged-units/61331/14 AND http://forum.mikrotik.com/t/mikrotik-routerboard-sxt-5d-16db-antenna-weather-concern/44629/44
example normis say it’s outdoor device in http://forum.mikrotik.com/t/is-the-mikrotik-sxt-lte-kit-rbsxtr-r11e-lte-waterproof/122027/2
But when you must use 2x ethernet in SXTR and ground cable… then you have problem and must do cutting in plastic cover/box…
if you not give feedback then nothing will change, write with picrutes/logs/story etc to support@mikrotik.com