Wifi connection

You have two completely independent radios that can reach the internet from your iPhone, cellular data and WiFi. Your phone chooses the preferred method of reaching the internet at the moment based upon cost per kilobyte of connection. Since WiFi is typically free of per-kilobyte usage charges and limitations because it does not travel over the cellular telephone network, whenever a WiFi signal is available, your phone will favor it over Verizon, where you probably have a monthly cap. Cellular data is provided to you by Verizon. When no WiFi service is in range, the phone will fall back to using cellular data over Verizon's cellular phone network.

Now, you made one more comment wherein you mentioned your husband. If your husband can connect to Comcast's WiFi (away from your home, I presume) when you cannot, then your WiFi credentials for Comcast's public hotspots are probably not in order. I recommend that you compare your configuration to his. This is easiest to do when you are together and he has a connection and you do not.

When you see this phenomenon, open both of your phones to Settings and look at the network name that your husband is connected to and you are not. Comcast uses about half a dozen network names, and you might not have all of them memorized by your iPhone. Also, you may need to download and install the Comcast app for locating and connecting to Comcast hotspots ( https://itunes.apple.com/us/app/xfinity-wifi/id549643634?mt=8 ).

The bottom line is that you have your husband's phone to compare yours to. Good luck.

Have you tried forgetting the network and reconnecting for reassigning your IP address from DHCP pool. At times when you move from one network to another the wifi at times does not immediately get hooked on to home wifi. 

Consider more secure wifi configuration.

Change your router’s WiFi to use WPA2-AES (CCMP) with no WPA or TKIP. Updating this setting ensures that your devices always connect in one encryption mode

1. TKIP is obsolete and not considered secure. Choose WPA2, the latest encryption standard, with AES encryption for optimal security
2. If your router doesn’t specify TKIP or AES, the WPA2 option probably uses AES

You can only get a WiFi connection on your phone when you are in range of a WiFi access point. If you are a Comcast customer and have Comcast's WiFi credentials installed on your phone, then any time you wander into range of a Comcast hotspot your phone should connect. If you are out of range, you will have no connection.

Is this your case, or is it that when you are in a business that advertises having a Comcast hotspot you are unable to connect to that hotspot?