So we put in a much better router (higher-spec Draytek 29xx series) and much better speed but we observed problems on the link.
I was suspicious that VM had configured things correctly because our install was a bit of a rush job, it was brought forwards (I think they had a spare slot due to a cancellation). They deployed a 2 box solution, an Alcatel OS6250-8M switch and a Cisco 2900 router. The fibre SFP terminates into the Alcatel, then the Alcatel into GigE 0/0 on the Cisco. GigE0/1 is then the customer-facing LAN. They need the Alcatel because the SFP slot on the Cisco can't be used as that would conflict with the GE-0/1. When he came, the Cisco 2900 hadn't been configured correctly, and the guy had to swap the configurations round on the interfaces. It was painful to watch him use a serial terminal emulator on windows and copy and paste!! It seems that the customer-facing port should have been set to auto and the link to the Alcatel to 100-fdx, but he got it messed up and so broke autonegotiation, as speed was fixed but duplex was auto. After a bit of experimentation we found the idea setting and now we get the full 50M up and down. Now we have control of the Cisco we are considering swapping round the ISP and customer facing interfaces so we can plop the fibre SFP into the Cisco (with due caution to check compatibility) so as to do without the Alcatel altogether.
