PS: To clarify, my subscription is with FL1 (FL1 Free! - https://fl1.li/de/mobile-abos/free), which uses the Sunrise network in CH). I have tried using the FL1 APN profile, and tried turning NAT Boost off, tried different Band combinations (incl. ALL available bands, all 3 bands shown for Sunrise (1, 3, 20), but none of this makes a difference (occasionally 4G+ is shown in the web-interface, but most of the time it just shows Band 3 only). System Log shows that Network Type is constantly (every 1-2 seconds) changing between LTE and LTE PLUS. How can this be fixed?

  @Sunshine 

Thanks for the prompt reply. Unfortunately I do not have another Cat6 mobile router (only my iPhone, though which I understand is probably a higher Cat class?).

Just in case, below is a screenshot of the available bands (FL1Test is my manually entered ISP/APN Profile, though situation is same with the Default Profile). Band 1 is selected automatically when I open the Band Search. I normally select then 3 and 20, as that combination provided the highest speed so far. However, on the Advanced Status page it shows Band 3 only (screenshot below). Any settings I shd change?

Thanks again 

@Sunshine 

Also, below is an extract of the (apparently) available bands in Switzerland by Sunrise (source: https://en.wikipedia.org/wiki/List_of_LTE_networks_in_Europe -- assuming this list is up to date?):

  @Sunshine 

Appears to be the same issue as with the "latest" MR600 v1 beta:
https://community.tp-link.com/en/home/forum/topic/579834?replyId=1129026 (and following comments)

  @kernash 

Thanks for pointing this out, Kernash!

@ sunshine   

Based on the discussion referred to by Kernash, I have switched to Automatic Band selection. However, even though initially Advanced Status showed Bands 3, 1 were selected, subsequently it was Band 3 only, and System Log shows again a constant switching between LTE and LTE PLUS.

What can I do to fix this?

Thanks again

@Sunshine 

Additional thought (of a layman only!): Is my understanding correct that the LTE modem is a separate PCI Card (attached to the Router)? And if so, is it possible to update the firmware of the modem card only? 

  @Sunshine 

Many thanks, I checked (with my main SIM card, same contract) as per https://www.tp-link.com/de/support/faq/3488/, and I can only see Band 3. Is there any other specific value I shd check?

But again, the System Log of the MR600 shows a constant switching between LTE and LTE Plus. And the Sunrise online network coverage map clearly shows 4G+ coverage at 100%.

And is it possible to simply "lock in" say B3 and B20 (both bands are used by Sunrise - see above) in the MR600?

Anything else I can do? If I speak to the Sunrise, what shd I tell / ask them? 

Thanks again

@Sunshine 

Hi, I am now in Germany and took the MR600 with me. But the problem remains, 4G+ is on and off. I tried, inter alia, the following:

1. Band Selection / CA set to Auto
2. Reboot
3. Advanced section showed CA 7+3
4. Basic showed 4G+
5. Speed test results: DL 109 Mbps and UL 12 Mbps 
6. Back to Advanced section: shows 4G only with Band 7 only

Thus, this seems to be a HW/FW fault. Pls can you look into this and see to get this fixed ASAP. I am getting a bit frustrated now as I am already spending too much time simply on testing...

Also, I noted that there seems to be a lot of data streaming in the background, even though I hardly downloaded or streamed media etc. Does the router send info to TP-Link etc in the background? How can I block this?

Thanks again