Fibre Speed issue

Hi all,

I wonder if anyone can help.

I have the Huawei HG663 Fibre Router, and I'm on a Fibre service.

I used to have regular broadband and I was receiving around 5-8mbps speeds.

When I turn my router on, I start receiving speeds of around 30mbps, which is great. It's slightly less than the speeds quoted to us, but it's still a faster service.

After around a day, the speed drops gradually, until it is around 3-4mbps.

It stays this way until I restart the router. Once restarted, I get the Fibre speeds of around 30mbps again.

What will be causing this?

Thanks