The 'EJ' suffix sounds like the regional identifier found on label attached to original packaging. eg. 'UK' variant comes with 3 pin UK 230v AC power adapter.
You have to inspect the underside of the actual router to determine whether it is the original EA6350 (v1), v2 or v3 variant.
Another way to perhaps identify a v3 from earlier v2 is from the original packaging. See some photos here:
https://forum.openwrt.org/t/best-openwrt-router-for-50/38795/13