I've a couple of 2862LT's on remote sites, with M2M SIMs in for fixed IP. I'm seeing, in idle state, very high data throughput per day, to the point where the ISPs 4GB limit has been hit on one and close to being hit on another within 10 or so days. Testing one at home, literally with no devices connected, it was doing close to 600Meg/day, some days lower. Anybody have an idea what could be causing this? I note in Online Status > Physical Connection it is reporting a speed, is it doing a speed throughput test periodically ramping up the data usage? I can't think of anything else that could be causing this, especially with nothing connected! Each Router had a LAN to LAN VPN connection, for management only, but I've tried disabling that to no avail (not that it should really make any difference without traffic across it).

Any thoughts appreciated, cheers.