@MikeMynis Hi, was your situation resolved? did the external poyting antenna work on your TL MR6400? I have the same problem with my router. i was thinking of purchasing the same antenna but i have to be sure it does work. 

@PeacefulCharles, after a bit more investigation, I decided to go for the omnidirectional variant: Poynting 4G-XPOL-A0001 Cross Polarised 4G Omni LTE Antenna.

This is because I did not have a 100% clear sight on the mast from my location.

I'm glad I did, because the antenna is superb. The signal went up from an average of 1 block to 4 blocks. Reaching speeds up to 45 Mbps.

But the TP-Link router is not that good. In another thread I also mention that the router drops the connection several times a day. With the help of TP-Link support, I installed a special test firmware, but at the end of the day, the problem remained. It's just a very unstable piece of hardware. It's the weakest part of the chain and I have to reboot it manually several times a day. No exceptions.

But the antenna is perfect!

https://www.amazon.co.uk/Poynting-4G-XPOL-A0001-Cross-Polarised-Antenna/dp/B00C1DGFPS/ref=pd_sbs_147_1/257-4076256-3741659

@MikeMynis hello, i did purchase the poynting xpol A0001 omni directional antenna and connected it to my tp-link mr6400. but the connection just became worst on the external antenna and when i tried to go back to the internal detachable ones it was worse too. From speed of 2Mbps (down) to 0.25 (down) and 2Mbps (up) to 4Mbps (up). Now i don't know whether did i do something wrong or what. I have a clear line of sight of the network tower and now I'm really confused. 

@PeacefulCharles have a look at the signal stength reading on the web console using provided rabbit ear antenna vs your external one. See if the externa is actually working. 

Stronge signal doe snot always equal better data transfer rates ->

If its working (boosts signal streangth as advertised) but speed test is repeatibly (test ist 5 X over an hour) slower its likley that while the signal is stronger, its also picking up more noise.

If you know your tower and have line of sight then a directional antenna may be much more effective - that would give higher signal gain AND include less noise.

Is what I rekon.  

@MikeMynis 

Setit to reboot automatically using the system tools-> reboot option.

And if that doesnt get youthrough each day, maybe less annoying to put on a timer plug  - the kind used to switch on a lamp when you are away etc - cheap.

So that  the power is cut proactively and forces reboot a few more times a day  - e.g. just before u get up and one at a set time early afternoon. At least then you may get infront of the unscheduled crashes and have a predictable downtime. Use this early afternoon moment to stretch your legs and have a cup of tea!

@AnthonyW1 No, setting a timer to reboot several times a day, is of course not a good solution.

I ordered a Huawei router. It will be delivered monday.

@AnthonyW1 thank you for the recommendation... I was thinking the same thing. I'm returning this antenna i bought and substituting it for a directional one

@AnthonyW1 i have submitted a return for the router and it will be collected. So i think i will have to look for a better router. 

@PeacefulCharles if you have clear line of sight to the mast, you should use a directional antenna. Not an omnidirectional one.
Only if you do not have cleara line of sight, you should use the omnidirectional one.

But, how is the 4G signal strength, and speed on a mobile 4G phone?

Maybe you can test that when you hold the phone outside, on the position where you have your antenna?

(Stupid question: you do have your antenna outside, right?)