Hi,
I have a Cisco Linksys E3200 here that has been running fine on LEDE v17.01.4.
Now I wanted to give the new OpenWrt V18 a try and flashed the newly available RC2 image for my router.
Right after the firmware upgrade Luci came up fine. But I noticed that v18.06.0-rc2 didn't detect my router as "Linksys E3200 V1" like v17.01.4 did, so I thought let's do a reboot and see if that my help.
However, instead of the Luci login screen I was presented with a page that was titled "Software Management Console" or something like that, which provided only a function for uploading a new firmware image to the router.
Before I did that I power cycled the router to check if it makes a difference, but it didn't.
Fearing the worst I flashed the LEDE v17.01.4 image via the above mentioned web interface and luckily my E3200 came up again and is running fine, even after reboot or power cycle.
After all that I did check in the bug reporting system for OpenWrt/LEDE and noticed that someone already reported this issue for a similar router and OpenWrt v18.06.0-rc1.
https://bugs.openwrt.org/index.php?do=details&task_id=1647
Since I somehow seem to be unable to register an account for the bug reporting system I thought I will just mention it here in the forum that I ran into the same problem with a Linksys E3200.