Rebooting cisco router every 3-5 weeks

We're a design studio currently using an 1811 Cisco Router on a 10mbps
Fibre connection.

Once every 3-5 weeks, we'll face a situation where the our internet
connection will completely drop off (ie: workstations in the office no
longer have access outside our network).

The only way to bring back our connection is to physically switch on/
off our router. Can anyone tell me why this might be happening? Poorly
configured router? Problem on the ISP's side? As far as I can tell the
router dies while someone is in on VPN, thought I can't confirm this
is the case 'every' time. Any ideas?

thanks,
ev

designev wrote:
> We're a design studio currently using an 1811 Cisco Router on a 10mbps
> Fibre connection.
>
> Once every 3-5 weeks, we'll face a situation where the our internet
> connection will completely drop off (ie: workstations in the office no
> longer have access outside our network).
>
> The only way to bring back our connection is to physically switch on/
> off our router. Can anyone tell me why this might be happening? Poorly
> configured router? Problem on the ISP's side? As far as I can tell the
> router dies while someone is in on VPN, thought I can't confirm this
> is the case 'every' time. Any ideas?
>
> thanks,
> ev

The Router may have exceeded the DHCP range ?