I have friends who live where there might be 1 bar of cell signal—just enough for a text message to drift in occasionally. Other than that, they have to take a motorbike to another location 10 minutes up the mountain. 
 

Does anyone have experience with a 3G/4G router or cell phone repeater that could actually function with such a weak signal?

 

 Any suggestion for the highest gain antenna for 2G/3G/4G bands?

 

i purchased a cellular repeater, and it seems to make a negligible difference. And I have 2-3 bars of signal at my house. One friend has the same repeater at his remote location, and it is useless (Though it has an antenna, it always says it has no signal.)

 

 Any suggestions?

Try different network sims, 50 baht each max

What provider is he using? I assume he receives a 4G signal.

Serious antenna stuff needs to be placed outside and best on a pole (and directed, try and error).

What's the next major city where you might find specialists/shops that have such equipment.

Also worth browsing online.

https://www.lazada.co.th/tag/4g-outdoor-antenna

(change to English)

3 minutes ago, scubascuba3 said:

Try different network sims, 50 baht each max

You were faster. From experience DTAC is worse in remote areas.

For me here much weaker than AIS.

Can't contribute about TRUE.

For Android phones(!) there are apps that give precise numbers for the signal strength.

I use "Network Cell Info Lite".

A troll post has been removed.

There are also signal repeaters but you'd need to know exactly which frequency your telco is using in that area, as some are using different frequencies at different locations.

 

3G/4G repeaters with massive antennas basically are about the same thing that telecom would use, just a bit more tame and for a home use, not to rebroadcast signal miles around.

 

Example: https://www.lazada.co.th/products/8km-3g-4g3g-umts-850-1800-210024dbi-i2887027135-s10535925900.html

 

But really, don't buy this unless you know what frequency your telco is using as buying wrong one won't achieve anything.