I havea 2860vn
i have read some posts about, say, routing all of a subnet via a dongle on Wan3 but the response was unhelpful in my case ('er just set up a load balance policy')
as if it were that simple
If I set up a load balance policy to route everything via the USB dongle (because it is faster) then I simply cannot see the internet
If on the other hand I disable the (slower) adsl then everything works fine over the 4g - so it is not the dongle or the 4g network

Must be how I am setting up the load balance policy ?*! I edit, say, rule 1, I speecify the range of IP addresses on my main local subnet - detination is set to 'any'
on next screen I select 'redirect all packets to WAN3'
on next screen I accept the default 'Force NAT' (not sure about this )
an then finish - the policy is enabled and hey presto No internet access - disable the policy and we're back online

Consequently I haven't a clue how one sets up such policies

FWIW what I wanted to do was to route ordinary internet requests via the 4G dongle and VOIP via the standard adsl and of course fall back to ADSL if 4G unavailable - but I'm completely confused as to how this can be done - there seems to be no more options