Its a modem/router which 3 has 1000GB data limit on which will connect to the near base station which has antennas or mast on them due to 5G having a high spectrum it works better outdoors than indoors same as 4G.
Have you ever wondered ah why is my phone not working with 4G indoors its the same reason and the most places 4G will work is by the window or balcony as most 4G and 5G mast work better outdoors due to their spectrum it really depends on how much your area is coveraged which is important to note.
Use the comreg website they are the organization that looks after the sites/cell towers.
The way you can test if you are getting 4G or 5G is it will show a specific colour on your broadband and if it turns on for 4G that means its 4G and same if a colour turns on for 5G it will be 5G.
I will classify it as a mix of both due to its being connected to the cell tower which most consumers do with their regular phones and getting signal from it.
If coverage isn't good inside of your home maybe a visit outside will help a coverage a bit as there is less barriers outside than inside like for e.g. thick walls,too far away from cell tower,what spectrum bands like GSM/2G, UMTS/3G, LTE/4G and NR/5G the cell towers have. If you live near trees or area that is heavily wooded area signal would reduced a lot there is a reason why radio waves work better in urban areas and areas that are open spaced as radios can pass through easier and the more base stations there is the better the signal.
Do a test on your phone you can check for your signal if your on android go to
- Tap Settings.
- Tap About Phone.
- Tap Status or Network.
- Tap SIM Status.
- Your dBm is under Signal strength.
