I live in a remote area in the EU, internet connection for our home provided by TL-MR6400 (V2) 4G SIM router. 

We frequently experience very weak signal or loss of connection; in damp or foggy weather it is even more frequent.

We modify the router position in the house frequently if facing bad service, sometimes we find a better place with higher signal strength, sometimes not.

Also, many times the router shows 2-3 bars as signal strength, but we see no service on the laptop or the phone (connected through WIFI (we have a Tenda extender, so not the WIFI is the problem)) to the router?! And my wife's iPhone (using the same mobile internet provider company) still receives 4G signal and operates!

After I restart the router usually (not always) get acceptable level of service. But it is disturbing, must solve somehow. It is not OK to restart the router 4-6 times / day, and also can’t work from home if you continuously hear/see lag in a Teams meeting.

I checked the router settings, modified all suggested settings, still far from the expected service level.

Searching the net and this forum about the topic, I learned a lot, but still confused.

To gain more stable service I found 4 groups of solution (not considering moving to a place I get better signal…):

1. Change router position

2. Use a network amplifier
3. Change router
4. Install external LTE antenna 

My main question: what sequence would be the best to follow? Which one to skip?

1. I’ve changed router position and the LTE antenna directions many times. no significant improvement expected from this. (According to antenna position: I’ve learned the vertical is the best for 4G. This is not what I always experience but let believe it…) Firmware update could make a difference? Band selection???
2. network amplifier (easiest to manage) could gain anything? Could it work? Install between the removable LTE antennas and the router? This is the topic I found the least amount of trustable information, no idea it is worth to try or forget it..
3. next level of change would be replacing my TL-RM6400 with a TL-MR600 Archer. I don’t know if it gives any better service quality with my location’s conditions. Not clear if the MIMO 4G+ method will provide any gain, or it is just doubling speed rate if signal is strong. Or is it any 4G SIM router which has higher gain in signal? 

4. Seems to mee the last resort is to use external antenna. Biggest investment, build a pole to get antennas high enough to go over the surrounding trees, find the proper direction and settings…It looks like a lot of trouble, many ways to fail, multiple loops of correction may necessary. Anyhow, the post from this forum by John vk3hjq is very useful, he had a lot of practical information compiled and shared, thanks for that to you, John.

https://community.tp-link.com/en/home/forum/topic/272342  

I tried to find an experienced network specialist nearby, but all I got was just hints and believes. All of them was located in bigger cities, could not found a guy, who knows what he’s talking about and still would spend the time and effort to come, visit my place, define options, discuss list of actions to the path to success. It is just more mess than money for them...

This way I have to solve this myself, but it would be really helpful if you share your point of view and experience. What is pointless, what is worth to try, don’t do it, or if you go toward this direction be aware of these risks or make sure not forget to pay attention to this detail…

So does it worth to try the amplifier?

Should I try the Archer MR600?

Did I miss something and should be check it first/before any bigger action?