I've read a number of posts saying that it isn't possible to bond ADSL connections as the ISP has to make a change to allow this to happen. However, is this also the case with USB WAN ports? I have a Vigor 2860n and two identical 4G dongles (one on o2, one on EE). Is it possible to join these connections together to double my 4G speeds. We do online video streaming from a broadcast truck, and I'm keen to increase quality of broadcast. What I really need is loads of upload speed glued together! Is this possible??

No it's not possible. How would a host (web site) know to send the data to two different WAN connections. You have to use a 3rd party service or an ISP specifically providing the service.

So is this wrong then: http://www.draytek.com.au/how-to-double-your-internet-speed/ ?

No it's not wrong. It's referring to total bandwidth across multiple sessions.

You referred to bonding and 'gluing' and a different application requirement..

I see. Ok thanks for your help