Improving Comcast modem signal

My ethernet speed is 25-125 mbps. I am using an old Apple router with Comcast rental modem. 5 years ago, I bought a Netgear modem (I don't remember the model)  to replace the rental modem and it never gave me wifi signal, so I went back to Comcast. I don't use Comcast landline phone. I am going to try to get a new modem. Do you like Arris > Netgear?

I just replaced my Comcast provided modem with a Netgear CV1000, which is a docsis 3.1 model. I'm continuing to use my own separate Netgear router. Connected to the latter with Supra Ethernet cable is a Google mesh network with a total of 3 access points. 

Before swapping out the Comcast unit, I checked the speed: 290 Mbps (I pay for 300). After replacement with the Netgear unit, my speed is 90 Mbps. Still fast enough for 4k streaming, but certainly a lot slower than it was. Funny thing is, my signal strength is very good, somewhat better than before. I had to have Comcast CS assist with getting the new modem online, ran into a hard stop with their app. Wondering if another call to them could improve my speed...

Anybody come up with an LPS for the latest Xfinity cable modem? I bought an iFI DC purifier but it did not have proper adapters with it. Would really like to try a LPS if anybody knows of a fit. 
thanks

I will say this 5 years ago I purchases a wireless gateway from Motorola and it's worked just fine and still does. Looking back at that point at 15 years of rental fees it was the only choice to make.

I hear ya. It just works and I am tech challenged. I will try a decent 12 v LPS and see if I get a nice bump