@jimas 

I don't know i i can write info about VPN because I am connecting to my office network and this employer information could be confidential. The problem is only when I use Virgin SIM card in MR200 witch is extremely strange. When i use another SIM card internet provider everything works. When I put Virgin SIM to another device such my phone or Huawei Mobile Wifi Modem everything works like a charm. When i go 50km to another place to connect to another BTS notching change. I am going to sell this MR200 because it is now useless to me. 

@jimas 
Virgin has non public variable IP addresses of two ranges: 185.135.2.0./24 and 205.201.22.0/24. They say to check if the problem appear only on one of this ranges and firstly i notice the problem occurs only on 185 but next day the 205 are problematic either. I set the NAT port like this and no result.

when i go to https://canyouseeme.org/ and paste 3389 i have "Error: I could not see your service on 205.201.55.22 on port (3389)"message.

@maxpayneau Appreciate this is a bit old now, but wanted to reply after having several similar issues this week. I had a 3 mobile PAYG data SIM which I was using with my new Archer MR200. Everything was working well, but I wasn't able to make an external RDP connection. I put the SIM in an old Huawei dongle and was, all of a sudden, able to make an external RDP connection. I then applied all of the recommended NAT settings on MR200 with port 3389, but no joy. I tried putting my paid o2 SIM in the MR200 from my mobile and absolutely everything worked, with and without the NAT settings. In light if this, I bought a PAYG o2 data SIM. Things got weirder here, as the SIM wouldn't work in the MR200 at all, but worked fine in the dongle including RDP connections. After looking at the text on the o2 SIM packaging I noticed that 4G was only subject to availability. The MR200 had been set to 4G preferred during all my tests. I switched it to 3G only and the o2 SIM started working and even allowed me to make the RDP connect. I then put the 3 mobile SIM back in the MR200 and got the same results. Finally, I switched the MR200 back to 4G preferred and left the 3 mobile SIM in there. Since then internet connectivity and external RDP connections have remained stable. I'm wondering if this is an issue with MSPs and PAYG SIMs? Whilst it's stable at the moment, I suspect I might have to set the MR200 back to 3G only during peak times if I need to make external RDP connections. Apologies if this doesn't help with your problem, but I thought it was worth sharing.