I haven't seen this issues at all with my R7800 and Voxels FW, nor other FW versions. The only process I use is when I update stock FW, I factory reset the router, load the FW file. Let it process. Factory reset the router once more, clear all browser caches, then go in and set up the router from scratch. After migrating to Voxels FW for the first time this would be needed. After one has migrated to Voxels, you don't have to factory reset, just update the FW and continue.
I recommend using IE11 or FF browsers only for doing FW updates. Seen odd and bad problems when Chrome is used. Also disable temporarily any PC security SW and add-ons. These can interfere sometimes.
I play it safe then sorry when it comes to browsers and FW updates.
You should be always LAN wired to the router with a PC or a laptop for safer upgrades.
I just loaded v47SF on my R7800 and had full access and control after the update.
I recommend doing a full factory reset, use IE11 or FF, be wired with the router, send the FW file. Let it process. Clear browser caches. Ensure your network is set for automatic IP addressing. Check to see it gets a 192.168.1.1 address. Then open IE11 or FF and you should get the wizard page at 192.168.1.1. If you get this, hit the reset button to factory reset the router once more. Then walk thru the set up wizard and configure the router.
Should all good after this. If it is, then just update to the next version of Voxel FW when it comes out. No need to reset. Remember, use IE11 or FF for FW updates.
next time animated gui might be eye catching.
I always face this issue Voxel. Everytime i upgrade the firmware 1 sub version i dont get the net working nor the router gui accessible at all. It atlease demands 2-4 reboots which includes hard power off.
this time also its same. I am facing it for past 3-4 versions.
1st time no net nor router inaccessible.
2nd time no wifi access says password incorrect.
3rd time no net .
only 4th time everything working as normal