Nighthawk Mr1100 will only work with two devices connected

Hello Faircloth04,

Welcome.  I'm and end user just like you.  But, let's see if we can get to the bottom of your issue.

Just some details to keep in mind:

Cellular service in many parts of the United States is pretty slow.  I assume you have AT&T?  So depending on where you live, how far you are from the cell tower, how congested the cell tower is, and how far your wireless devices are from the hotspot, speeds can vary widely.

For example, with one device, on a 5GHz, 40 or 80Mhz Wifi, close to a good cell tower, you might get 60-100 Mbit downloads.  Use tools like Fast, Speedtest, and SpeedSmart to benchmark your connection.  In contrast, if you are far from the cell tower, are using 2Ghz, 20MHz Wifi, and you have a handful of wireless clients all trying to watch YouTube from across the house you are going to have issues.

Let's start with your cell phone.  Make, Model, OS version.  For example, I have an iPhone 6s running iOS 11.4 on AT&T.  Using a speed test app (like Fast.com).  I get speeds on my phone anywhere from ~20-140Mbit down depending on the tower, how close I am, and how busy it is (aka time of day).  Fast is a good one -- its from Netflix -- very reliable indication of network performance.

From my experience, with the settings fully optimized on the Nighthawk (5Ghz Only, 40Mhz, Long, Auto) I can ALMOST match the performance of my iPhone 6s.  That is to say, I can usually get 20-60Mbit through the Nighthawk.  Performance is very good for my two sons in the car who stream YouTube nonstop on their iPads while playing online games simultaneously, as my wife does email and telecommuting on her laptop.

From a performance perspective, I doubt your device is to blame.  It is most likely (not in order):

1) the Cellular network in your area and/or your distance from the tower -- compare to your phone

2) the wifi settings you are using on the hotspot and/or wifi "noise"/collisions in the location you're trying to use

3) Wifi client related issues -- too far from hotspot, old wifi (2.4Ghz), out of date drivers, etc.

Step 1 -- make sure your phone is working well

Step 2 -- unless you absolutely need 2.4Ghz wifi, turn it off, and use 5Ghz.

Step 3 -- 40Mhz @ 5Ghz is more than enough bandwidth.

Step 4 -- Be sure you have 802.11ac turned on, be sure you change the transmit power to Long, and channel selection shoudl be "Auto"

Step 5 -- Join a single modern device (iPhone, Samsung Galaxy, Recent laptop with 5Ghz) to your hotspot

Step 6 -- Run your network benchmark tools (Fast, SpeedTest, etc.) and record the speeds at different times of day and different distances from the cell tower

Step 7 -- When you begin to test with multiple devices.  Simply joining (aka associating with the AP) several devices will not slow down the network UNTIL you start to transfer data from those devices (cloud syncs, backups, streaming audio/video, etc.)  NOTE that on many devices some of this chatter happens in the background and often waits until a network connection is available.  So you may not reliaze it's happening.

Step 8 -- when multuple devices share the same wireless access point, each can theoretically achieve peak (up to the capability of the wireless backbone -- aka your 20-60Mbit from AT&T) when used individually.  But if multiple are active all at once, ALL wireless access points act like "hubs" that is to say a single air interface collission domain.

So very roughly speaking:

If one device can do ~40Mbit alone.

Two devices simultaneously downloading might get ~15-18Mbit each

Four devices simultaneously downloading might get ~5-8Mbit each

Because there's a lot of chatter and collission overhead in the Air interface which multuple clients are trying to talk.  This is greatly exasserbated with older Wireless protocols like 802.11a,b,g, and even n.  On 2.4Ghz at 20Mhz, not only is there a lot of channel interference from your neighbors, and chatter from your clients, but the total bandwidth of the connect is only around 25Mbit sustained -- best case.

So, while the Nighthawk can do 2.4Ghz wireless, I wouldn't suggest you use it.  In contrast 5Ghz 40Mhz can support more than 100Mbit (without going into the technical details of multiple spatial streams and different signaling schemes).

Don't believe any of the nonsense you see about "Gigabit" hotspots.  If you're getting 60-100Mbit you're doing great.

-Jonathan