Mobile Wi-Fi, also known as MiFi, uses your smartphone’s mobile data connection to establish a wireless signal that compatible devices can share to get online. It’s particularly handy when you are travelling and not within range of a standard Wi-Fi connection, or as a failsafe for flaky or overloaded home broadband.

A mobile Wi-Fi connection can be created by the smartphone itself, using a process known as internet tethering, or by a portable device called a mobile router or a mobile hotspot, into which you insert a SIM card.

When used frequently, mobile Wi-Fi routers can be the preferred solution because they won’t drain your smartphone’s battery, there’s no fiddling around with swapping SIM cards, and you won’t need to leave your phone with whomever is sharing its internet connection. They can also be used with data-only SIMs (those that do not offer calls and texts), which can make it cheaper to get online. 

The difference between a mobile Wi-Fi router and a mobile data dongle is that a router does not physically connect to your device, and it can share a mobile data connection with more than one device. These days, USB dongles are really useful only for devices such as old laptops and PCs that do not support Wi-Fi connectivity.

You can connect multiple devices: Some MiFi devices let you connect 10 or more devices to a single hotspot, which will work out a lot cheaper than paying for a mobile data plan for each of those devices – but you’ll want a generous data allowance.

You can connect Wi-Fi-only devices to a mobile data connection: Tablets are great to use at home, but what about on the train, on the beach or by the pool? Wherever you can get a phone signal, you can use MiFi to create a wireless network and get online from any Wi-Fi device.

You can save money on your next tablet: Buying a tablet with a 4G or 5G data connection adds around £100 to the price, and that’s before you consider the monthly fee for your data. Use some of that money to buy a MiFi router instead and you’ll never need to buy a cellular tablet again.

You can reduce roaming charges: Most mobile operators offer free roaming in the EU (for now, anyway!), but fixed-fee roaming elsewhere, allowing you to take your home tariff with you for a set cost. Rather than paying this extra charge on all your devices, turn off data roaming on them and connect them all to a mobile hotspot. You’ll pay this charge only once, but get all your devices online. Note that 5G roaming is not widespread, but it is currently offered by Vodafone and VOXI.

You can avoid using slow hotel Wi-Fi: When visiting hotels that still charge for Wi-Fi, you can get the kids online all day and at a lower cost than what the hotel would charge. Better still, you can avoid using the same network as all the other guests, which is usually slow and often has poor signal in your hotel room. Sometimes these networks can also be unsecured, so using MiFi will be preferable.

You can add 5G connectivity to a 4G device: Many of us have yet to jump on the 5G bandwagon, but where available it is seriously fast. Although your phone may be limited to 4G, your data plan almost certainly includes 5G. A 5G mobile router will allow you to connect your 4G phone to the internet at 5G speeds.

You can get faster download speeds: Even if your device already supports 5G, you could potentially get faster download and upload speeds by switching to a MiFi that supports a faster connection. Just remember that 5G is not yet available everywhere, and purchasing a 5G hotspot will push up the price.

You can share storage across your own mobile network: If your MiFi supports a microSD card, you can share that storage across all your devices, which is especially handy if they don’t support expandable storage themselves.