one way to test signal strength is to install a free wifi signal analyzer on a smartphone. I installed one a few years back to check signal strength at the plant. you can test in all areas of your home and walk towards the router to see where you have a problem.

Surprised no one suggested a mesh network that connects directly to the modem. We use a Linksys Velop tri-band mesh network in NY with 20 devices connected simultaneously with great results. It was an expensive solution but eliminated dropped connections and contention for router access. WiFi connection speeds are the same throughout the home.

Try using a wifi signal analyzer on a mobile device as suggested by Dgodin.
I downloaded the Google Play "NETGEAR WiFi Analytics" app to my tablet and used it to identify the networks around me.
This wifi analyzer has a page that shows the number of networks in your vicinity and the channels their modems are using. Your modem and channel should be easily identified - it should be the strongest one and at the top of the list. See if any of the other networks are using the same channel as your modem/router. If they are, change your channel to one that is not being used by a neighbor.
You will need to get into your modem/router setup to change its channel.
I had a similar problem that took me a long time to solve. I was trying to get a wifi signal out on my lanai so I could stream music outside. As soon as I went on the lanai, the streaming stopped. I thought the concrete wall was blocking the signal from inside the house. I tried using a wifi extender but only got poor results on the lanai. That is when I tried the Netgear analyzer and found that 2 of my neighbors were using the same channel that my modem was set to (1, its default). Outside of our house, their wifi signals became strong enough that my wifi was getting overpowered. There was no problem inside. After changing my channel to one which none of my neighbors was using, I had no problem getting a signal outside of my house.
I hope this helps.

We just changed a whole lot of hardware from Playschool stuff to almost all Apple. We didn't have enough jiggawatts of power to keep everything running happily together. We went to Comcast, fingers crossed and added a Linksys extender from Amazon for about $70. All ins well at this juncture. We notice the difference in speed, time will tell and so will I. I just don't like that it is a yearly contract but the price is so low it wouldn't hurt too badly if they foul up!

Found this out the hard way about 15 years ago on a long road trip. :oops:

Could not get a wi-fi signal from the hotel, was panicking... and called a computer store.

The person mentioned the wi-fi button...and asked it if was lit.

Pushed the button and then my wife and I looked at each other...and just laughed like the dummies we were. :D

Wifi signal
 

Again, thanks to all who replied. I wasn't aware of apps that can check WiFi signal strength and will now pursue that fix.

I use Acrylic Wi-Fi Home to check WiFi signals.

I haven't seen any follow-up on your original note that wife's laptop couldn't find any wifi, not just your own, and would not even try to find one. As so many people here have wifi unless you have an isolated home out in Fenney, there should be many networks detected by the laptop. That is what makes me suspicious the problem is in the wife's laptop not your router. My laptop now is showing 7 networks other than my own.

Here is a google search that gives many suggestions of things to try:

laptop won't search for wifi - Google Search

Weak wifi
 

The problem was the router, not the laptop. I got an app, at the suggestion of another TOTV poster, that measures signal strength. Signal was in the "poor" range. Comcast confirmed my router was dated (2 years old?) and is sending me one with greater range.

And now you know.

The new Comcast modem/routers are pretty good. We picked up a new one in May and the signal strength in our house has gone up quite a bit. Our Samsung smart tv previously showed us a signal strength of around 10 Mbps and now tests in the 70 Mbps range. Curiously when I set my iPhone down next to the tv it tests around 90 Mbps.

Still not convinced that it is the router. You haven't gotten the new one, so I (as a previous MS elevated tech) wouldn't consider your case closed, yet.
BTW make sure that your new router handles the latest 2013 transmission protocol 'AC'. Older ones' B' 1999, 'G', and 'N'. Best to have a device that will best handle your future devices. They recycle older modems so your 2 yr might actually be much much older. Look up the specs on your laptop WiFi card find out what transmission protocols it supports. 'AC' is the latest.

If the new router does not solve your issues, buy a USB dongle 'N' WiFi adapter, $10-$20 for the laptop.

I have seen WiFi signal strength in offices/ homes compromised by a dimmer light switch, wireless phone, wireless home theater speakers, older microwave ovens, and LCD blubs just to name a few. I also wonder if you have gotten any new appliances or WIFi devices. 2.4MHz and 5MHz are the WiFi ranges that are currently in popular use. 2.4 goes through walls/ material better and longer but suffers from slower speeds and bandwidth clutter. Even 1 other device that operates at a lower protocol could severely compromise overall system performance. I usually explain it this way: My Lambergini can go 200mph. But one of my tires is flat so I can't go over 10mph. In designing high-end PC's the performance falls to the weakest link. Networks can be affected similarly.

Keep us posted.

(Posted the above as general information so others could diagnose similar connectivity issues.)

agree on some of your points .. First an AC router is required for optimum performance .. But, most likely the current router picks the broadcast channel automatically .. recently there could have been some environmental changes affecting that selection .. The OP might not have the skills required, but it is relatively simple to go into the router and set the broadcast channel .. An internet search will reveal the allowed channels for 2.4 and 5 ghz transmissions .. that will show the "best" alternate channels to broadcast via trial and error ..

Weak Wifi
 

I appreciate these tech responses, but you are way out of my pay grade.

Linksys Extender AC750 Boost. Security wise if you select WPA2 are you secure? If not what is the correct thing to do?

Works great just security minded.

If you are a Comcast customer you should go to Xfinity.com and test your wifi signal with their speed test app. Do you know what wifi speed you are paying for? If you are only getting speeds in the 20s then I would let Comcast know and they will fix it. I had a similar problem and they checked it out and ended up giving me a new router that is capable of 400mps. That definitely solved the problem. I pay a little more but definitely worth it. I like you also only stream TV with Roku and Hulu and the faster the speed the better ie no buffering.