Just traded up for the newest Comcast router. I live in a two-story (with the Internet on one end of the house), and getting Internet to all parts has been a challenge. It has the dual band setup, so I have these questions:
It is my understanding the range of the build in WiFi access point on Comcast modem/routers generally is not that great. This is has also been my experience and I have had at least one Comcast customer service person agree. As a result, I personally don't use the WiFi built into my Comcast modem/router. I have two separate routers...one for my use and the other supplies a network for close family to use and one for guests to use. Both have better range than the Comcast modem/router. Like you, my routers are at one end of my house (the back end). If you do go with a third-party router, you can put the Comcast modem/router into "bridge mode" that will turn off the router and WiFi functionality on the modem/router and then use the third-party router.
1. I did change the SSID and password, but it asked me to choose between N/AC antennas. Should I limit the 5ghz to just AC (for my Firestick and Chromecast), and set up everything else (Harmony Smart Hub which only seems to like 2.4, old Windows laptop) to 2.4?
That is kind of up to you and your use. It will depend on what devices you have that can use 802.11ac, 802.11n, etc. Generally, the 2.4 GHz band will have better range, but has higher chance for interference and cannot attain the speeds of 802.11ac running on 5 GHz. 5GHz will generally have less interference, but will have more trouble getting the signal through obstacles (i.e. walls, especially masonry wall, etc). So, the real question is do you have an 802.11n devices that don't work well on the 2.4 GHz band due to interference. If so, then you might want the 5 GHz band to use the 802.11n chipset/speeds rather than 802.11ac...unless you really have devices that can take advantage of the speed/throughput increase of 802.11ac. Tthis will generally be something like a laptop that is transferring data to another computer that is connected by 802.11ac or Gigabit ethernet...things like a Firestick or Chromecast will generally not benefit that much from 802.11ac other than maybe better range as a Firestick or Chromecast is generally bottlenecked by the speed of your Internet connection. And unless you have an Internet connection that is significantly faster than 100 Mbps, it will be your bottleneck for most things.
2. I also have a home wiring system, and have been running as many wired connections to my devices as possible through a DLink Green switch and Gigabit boxes where I have multiple connections. All of my wiring is Cat5, including the wiring leading from the wall. To ensure I'm getting the fastest wired speeds possible, do I need to upgrade any of the wiring from the wall to the devices?
It depends on the devices you have and the things you do with those devices. Only if the device itself is capable of Gigabit ethernet (i.e. has a Gigabit port) AND you use that device for things that can take advantage of those Gigabit speed would you then potentially be interested in considering upgrading to Cat5e or Cat6 cabling. And note that ALL cables and network devices (switches, routers, etc) the send data between two Gigabit devices (or between a WiFi device capable of more than 100 Mbps and a Gigabit device or two WiFi devices capable of more than 100 Mbps) would need to be Gigabit compatible. A cable in the wall that is only Cat5 or a FastEthernet (100 Mbps) network switch (either stand alone or built into a router) would be your bottleneck making using Cat5e or Cat6 cables else where a waste. And generally, the only function that benefits from Gigabit is transferring files across your local network between computers. This is because generally most US Internet connections are still less than 100 Mbps and even if you do have a faster connections, odds are it will not be that much faster than 100 Mbps. Unless you are lucky enough have Google Fiber potentially with 1 Gbps or something similar, odds are you are bottlenecked by your Internet connection.
FWIW, I have a Comcast connection that typically gets me at least 75 Mbps. I do use either Cat5e or Cat6 cables throughout my network, but some are Cat5 patch cables. All of my network switches are Gigabit switches. The reason for this is that I have a Network Attached Storage (NAS) device and all my computers are Gigabit compatible. As a result, I do a fair amount of transferring data from my computer to and from the NAS, including backing up over the network to the NAS. These files transfers can benefit from the Gigabit speeds. All my other functions (browsing the web, checking email, gaming, watching streaming video, listening to either local or streamed music, etc) don't benefit at all from the Gigabit speeds, so technically any device that I ONLY use for those functions (my TiVo, my Apple TV, my Roku, etc) would be fine with Cat5 cables connecting them to my local network.
3. I would like to offer my friends/guests access to the 2.4 environment without them being able to access any network folders. How do I set up the modem so that everyone only sees the 2.4 and has access to Internet only?
As previously noted by Trikein
, unless your router has a guest network function, you will not be able to hide your local network from friends/guest that connect to your wifi network. And I don't believe that any of Comcast's devices do (although you have a newer model than me if it has 802.11ac capability). This is generally another argument as to why to get a third-party router. These days, many third-party routers will have a guest network function.
4. Finally, if I'm able to do #3, I'd love to hide the 5ghz entirely, and only grant specific devices access to it. Is that easy to accomplish?
Thanks for everyone's help in advance!
Hiding a network SSID is done by turning off the "Broadcast Network Name (SSID)" function (that is how it is named on my Comcast modem/router, but it could be something similar but different).
Granting only specific devices access to the network is called MAC (note: Note Mac as in Macintosh computers, but as in MAC, or media access control, address) filtering. What you essentially are doing is setting up your WiFi network to only allow connections from devices that have their MAC addresses pre-approved.
As noted by Trikein
, this can sometimes create more problems than it really helps. Hiding an SSID will not deter someone serious about finding your network as there are still ways to see the network SSID even if you are not broadcasting it. And MAC filters will not stop someone serious about trying to get into your network. As a result, I personally don't both with either anymore. The best thing to do is setup a good password while using WPA2 encryption for your WiFi network.