This has been discussed heavily in the beta thread if you are keen to go and have a read.I updated over a week ago and the temperature is still high
Those temperatures aren't great, but not critical. Mine hovers around that mark as well.
If you are using more than a single Ethernet port on the ac86u, then you will find that they can actually generate a bit of heat, and the last update disabled "Energy Efficient Ethernet".
You can switch that back on by running the following command.
pwrctl config --eee on
That setting should drop the temps a further 5 degrees or so. You will need to add that to a startup script so that it is re-enabled after a reboot.