So in my new home, my PC goes upstairs, but I wanted the Wifi on the middle story. (It's one of those Garage/Living/Bed three level townhomes) That way I figured I could get good wifi everywhere. After struggling with speeds upstairs, I went through a bunch of possible solutions. I have 150mbps cable, usually sits up around 180 though. However, my main PC was only seeing about 8mbps, and was kinda spotty.

First I moved the router to a more central, but less convenient part of my living room. This helped get my up to about 20mbps.

Next, upgraded my old network card. Got one with BT, so it wouldn't be a complete waste if it didn't help (which is nice, the BT on the mobo I have from '09 was useless), but also more importantly a remote antenna. Unfortunately the wires are only a couple feet long, so I can't do much, but get it out of the corner away from all the other wires. That helped a little. Went up to about 30-35mbps. But I was still only seeing about 20% of the speeds I should see. I also noticed at this point issues with my chromecast in my bedroom (basically directly above the router). 30mbps should be enough to stream 1080p without much problem. So it's more than just pure speed.

Next I tried to setup my router as a repeater, since the Xfinity modem has built in wifi. I planned on putting that upstairs. That was a disaster. Couldn't get it to work, and I had to factory reset the router.

Finally I thought I'd try to make separate 2.4GHz and 5GHz networks. I know 2.4 is better for going through walls and such, but can get crowded, and 5GHz may have a lower signal, but actually better speed. Boom. 180mbps. Turns out that new network card was actually helpful, I just had to force it to 5GHz. I wonder if there is a way to force it without making separate SSIDs