There are many 4 g Routers to choose from the battery Muama Ryoku 4g is with WiFi only.
Another is the 4g LTE Router with WiFi which is also battery powered.
If you want ethernet ports there is the Huawei 4g Router with 4 ethernet ports and WiFi which is mains powered.
The Huawei mains router costs £99. However, you can get it for £16 a month from Three. The Battery Ryoku 4g router costs £69 it comes with 10 international sims so you can travel round the world with it, which you can use in a tent if you wish. The charge lasts over day when in use. The 4g LTE router is only £30. On a 4g network you can get 150 Mbps if you are in a strong signal area. Now you can have Broadband on a laptop in your car with a 4g or 5g router and a 230VAC adapter in the cigarette lighter. See the latest at webhouses.co.uk/store under power.