Homespot router is lag spiking

I have a Homespot router with an O2 card in it. I keep getting lag spikes. I have restarted the router many times. I have reset the router many times. I have combed through my network settings on all the computers over and over again.

When I use my iPhone’s hotspot my lag spikes go away and everything works fine. As soon as I connect to the router (via cable or WLAN) I get the the lag spikes again. 

I have the router setup next to the window closest to the base station. The signal strength is good too. The problem is not the signal strength as my iPhone with less signal works better.

Since yesterday the problem has become worse. Now my device shows I am connected the internet but I cannot opena any webpages or get connections. If I restart the router the problem is fixed temporarily. 

I have spent many years in IT and have isolated the problem to the router. The router is faulty but my limited German means I cannot call the call center and my friend that speaks German can only come help me in a week or so. 

Is there anyone in the community or O2 that can help me fix this please? Thanks.

Edit by o2_Katja: Verschoben in unsere Englisch Community