I tried to upgrade my 2865 to the latest 4.5 firmware.  This failed first time with a message that the firmware was corrupted.

I was then able to upload the v4.5 firmware successfully, but then it just kept re-starting.

In the end I had to use the TFTP approach to re-load the previous firmware.  Fortunately this worked.  Then I was able to apply v4.5 firmware again.

I've been running Draytek rourters for many years and this is the first time I've needed to use the TFTP approach.