Intermittent internet issues

[chrbb]

We keep having random internet prolems within school, either none at all or very slow page loading. Our internet is provided by the LEA via a point to point system on our roof, apparently fibre was too expensive so the LEA have set up a complicated mix of fibre to some schools then point to point to nearby schools.

Admin and curriculum are seperate with the only common ground being the switches and the point to point 'gubbins'. So I've ruled out my new server and dns problems, but the LEA are convinced it's our network, maybe a loop. I've experienced a network loop before and it threw the entire network, couldn't access the server shares and the lights on the switches were going crazy. Is there anyway I can check the network with some free software and does anyone have any other ideas as to what might be causing the internet problems.