Antenna extension

Hello, the attached is a 4g wifi device however where i live the cell tower signal is very weak, how can i attach external antenna to it for better cell reception and hence better 4g speed

It would be difficult, and probably not very effective - even if it had an external aerial socket - the frequencies in use mean that losses in the connecting cable are high.

I would suggest a better device, and fit the device as high up as you can with an Ethernet lead feeding down to where you need it, and connect that to a WiFi access point.

I've got a Huawei B535-232 which works really well, and has two external aerial sockets, if required.

I'm having trouble seeing where the existing antenna is. Are there any conductors attached to or printed onto the inside of the plastic case?

I would like to see the existing antenna to give an educated guess about how much improvement is possible by connecting an external one. An internal antenna might have a gain of around -3 dBi on average, and possibly worse. Using an external antenna, you can shoot for roughly +5 dBi with something good, and suffer only 1 to 2 dB loss in a short cable. So the net signal improvement available might be on the order of 6 dB, which is not large, but still may be noticeable and perhaps worth the effort. I'm guessing that adding 6 dB of signal might be about half a bar on your signal strength indicator. It also might be worthwhile to run a longer cable despite the added losses. Getting some height on your antenna often pays off, especially at these frequencies.

About 7 years ago, I had a similar problem in a new apartment, where the only internet connection I had available, was by using a USB dongle with a SIM card. (I wasn't about to have the apartment wired for cable, as it was only short term and I wasn't concerned about having a TV)
The cell signal was mainly only 1 bar and once in a while, it would hit 2 bars.
There was a spare plastic lamp shade, kinda dish-shaped, left behind by the previous tenant.
I lined it with aluminium foil and used a USB extension cable to allow the dongle to be plugged in, in the center of the shade, then poked around with it near a window - managed to get 5 bars. That's where it lived for around 18 months, until I moved out.
Something like this may work too: