I've had the same problem. I never achieved more than 20 mps with unlimited fibre with regular cut outs that could only be remedied by re-setting the router. The Plusnet engineer eventually agreed that the router was at fault but refused to replace it unless I renewed my contract as I was within two months of its completion. I refused to do this and switched to another provider. I have just had a bill from Plusnet for leaving my contract early (1 day)! They should be paying me compensation for failure to provide what they advertised. It looks like Plusnet are going the way of BT since they were taken over. I would avoid.