According to this,

https://www.draytek.co.uk/support/guides/kb-transferring-configurations

I should be able to import my 2862 config backup into a 2865 router, both running the latest firmware, however when I try and do so, the router hangs and needs factory reset.    Is this a known issue?  Is there any workaround?

Thanks

 

I too would like to know the answer

It would be handy to be able to copy the config from a 2862 to a 2865ac (obviously, the network config, there being no WifI config n the 2862).

I had this problem.
Disabling IPv6 on the WAN connection seemed to mitigate it for me.
Not an ideal solution, but I haven't had time to do a factory reset and manually enter the config yet.