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[burakkucat]

The way I view it - and it may of help to you - is the regard the SXT, in its factory default state, as similar to a VMG1312-B10A in its factory default state. (A modem/router/NATer/firewall/DHCPserver/etc.)

So think of the steps that need to be performed to switch the VMG1312-B10A to a bridging modem and perform the equivalent on the SXT.

[Weaver]

Agreed. Mind you, I never configured a B10A to be a straight modem, because AA did the config for me. I first of all, bought one from AA, so that I would get some support initially. I then did fairly minimal changes to that config.

I think I need to find out how to expose an ethernet interface bound to LTE, and then bind a PPP client to it. I have found the latter but not the former. In the PPP client it doesn’t list any ethernet interfaces and indeed seems to be talking about devices that emulate a serial port and even understand Hayes modems (mentions ATDT commands) as in real genuine old dialup, such as I remember all to well from 30 years ago. Mind you some radio devices are configurable using exotic non-standard AT-commands. (Noted that when I was working on a radio that could send SMS packets over GSM.)

I upgrade the o/s to v7.4.1 (in the ‘stable’ sequence) and it now shows IPv6, yay! I may need to configure the IPv6 prefix if it isn’t going to discover it.

I haven’t yet discovered how to set an IPv4 default static route ie. to 0.0.0.0/0. It really really wants to be a DHCPv4 client, understandable, and that’s already working, although it gets some random IPv4 from DHCP still because I just haven’t got round to setting up the Firebrick with a static MAC-to-IPv4 binding yet. That will do it. It has two IPv4 addresses for its ethernet i/f right now: one configured statically and one obtained from DHCP. And it all works. I just like to know exactly what the IPv4 addresses of everything are.

I need to stop all this happy faffing about and a) RTFM, and b) concentrate on LTE as I’m not getting anywhere with that. I need to find out how to assess the state of LTE next.

[burakkucat]

It really really wants to be a DHCPv4 client,

I'm surprised as, from my reading, I thought the SXT's default state was as a DHCPv4 server. Continuing the analogy with a VMG1312-B10A, substitute LTE for the xDSL interface and that is what I expect you to experience.

I need to stop all this happy faffing about and a) RTFM, and b) concentrate on LTE as I’m not getting anywhere with that. I need to find out how to assess the state of LTE next.

A good idea. As I have never used nor handled such a device there is very little that I can add. I'll just keep watching for you updates.

[Weaver]

You’re absolute correct. The default config is with the device set as a DHCP server. I of course immediately deleted that object before it could start seizing other devices on my main LAN, as this isn’t a private link with just two nodes on it as a mere straight ethernet cable would be. It’s via ethernet into my main switch, and is then wirelessly talking to my iPad.

If you then add a DHCP client object, it seems much happier. The reason for unhappiness - if you don’t have a DHCP client object and just set a static hand-configured IP address - is that although you can set the size of the prefix, there’s not the usual field to specify an IPv4 default gateway. I haven’t found anywhere at all where I can do so. Some sort of routing rule to redirect 0.0.0.0/0 would do it but that’s going to be hard to find unless I do the right thing and get reading first. It really doesn’t matter though if I don’t solve this, as I’m fine using static DHCPv4 mappings determined by MAC address.

I’m reading https://help.mikrotik.com/docs/display/ROS/First+Time+Configuration#FirstTimeConfiguration-RouterwithoutDefaultConfiguration

One annoyance is that I can’t use the web CLI (called "Terminal" in the web ui) because I get a window and a command prompt but the web page doesn’t tell Safari that the page is waiting for keyboard input which would make the iOS virtual keyboard pop up. I can’t engage the virtual keyboard by hand either in this case; there’s sometimes a button that you can click on to make the keyboard pop up.

I googled this "PLMN search" thing and the answer I found was "can’t find any cell towers" - i.e. basestations, in English. I don’t understand that at all, and that’s not good.

[meritez]

PLMN search in progress" means the device does not see any compatible cell towers in the vicinity. SXT LTE supports only bands 3 and 7. Even if your operator claims they use these bands, they might not use it specifically on your tower.

https://forum.mikrotik.com/viewtopic.php?t=108619

A&A/3 don't use band 7, so only band 3 needs ticking.
We need to find band 3, where can you place the SXT, I used to put it on a window sill.

There may be another mast in the opposite direction to the way you are currently pointing it that transmits band 3.
Webfig not working sounds utterly annoying, you can telnet or ssh into the SXT if that's any help, though RouterOS terminal is a steep learning curve.
https://help.mikrotik.com/docs/display/ROS/Console

Safe Mode
It is sometimes possible to change router configuration in a way that will make the router inaccessible (except from local console). Usually this is done by accident, but there is no way to undo last change when connection to router is already cut. Safe mode can be used to minimize such risk.

Safe mode is entered by pressing [CTRL]+[X]. To save changes and quit safe mode, press [CTRL]+[X] again. To exit without saving the made changes, hit [CTRL]+[D]

[Weaver]

The thing is, my iPads use AA/AQL/Three SIMs exactly the same as in the SXT and I can see the basestation three miles away across the glen, straight line of sight and the SXT is right in the upstairs office window pointing at that basestation. I currently have a 3G USB NIC with a SIM of the exact same type and that is on AA/Three; this works fine with the same view eastwards. My iPad has been on 4G with AA/Three this afternoon (so I could still access the internet via 4G while wifi was stuffed because I’d set my iPad’s WLAN i/f to 192.168.88.xx) and works fine even though it’s not near the east facing window, but in the back (west end) of the bedroom. My iPad gets 3 bars out of 4 even though it’s not near the good east-facing window.

I notice it refuses to do an LTE scan (? channel scan?) with an error message that sounds as if this model doesn’t support that feature, or current particular hardware doesn’t support it. (Well they should have just displayed it as unavailable in the ui, with a very brief keyword to serve as an explanation, rather than letting you click it and then telling you you did a bad thing.)

I’ve just locked myself out again foolishly and Janet, my chief button presser, is asleep, so no more exploring until the morning. Will read manual instead.

Janet uses AA/Three in her iPad and EE in her iPhone. She has unlimited data, whereas AA SIMs are mind-bogglingly expensive per byte but since I’m using it for backup it’s fantastic, because there’s no huge standing charge every month, it’s only couple of pounds plus the cost of traffic, so it’s ideal.

I see this ‘bridge’ object, and happily following a random webpage of instructions, I deleted it and that was how I locked myself out just now. I thought I needed to find out exactly what this thing is; I assumed I’d be able to connect more interfaces to it (somehow, in the UI) and thus bridge the LTE interface to the ethernet. I realise now that that’s all nonsense; I need to create a PPP object and then associate that with LTE and then bridge-connect the PPP object to the ethernet i/f.

I noticed that it mentions a 1450 byte (L3 PDU ?) MTU for LTE, iirc. This is roughly the same unwelcome nonsense that I get from my current 3G USB ‘dongle’ NIC -1450 or 1440 bytes, I forget which. I think the mobile network as presented by AA/AQL has an IP PDU of 1500, perhaps no more, but that seems uncertain. It has to be larger than that at L2 because there is the 2 byte overhead of PPP, so that makes it 1502 PPP MTU, or if it’s PPP+PPPoE that would be a 1500+2+6=1508 byte PPP MTU. Am I correct, does the L2 MTU have to be at least 1502 bytes? If it’s greater than 1500, won’t it perhaps be L2 MTU=1600, or could it just be a (mere) 1508?

The reason that I’m thinking about this is that I wonder if I could keep the IP MTU at 1500 even though I’m using PPP? Another thought occurs to me; what about the overhead of ethernet MAC framing if you’re doing IP+ethernet over the LTE i/f ? That’s way, way greater than 1508.

[meritez]

The SXTLTE3-7 does not support 3G.
Your iPad etc are probably connecting to Band 20.

It would be interesting picking up both the Lyca and Lebara 1p sims to see what coverage you see from O2 and Vodafone.

[Weaver]

I asked Janet for definitive info on all the networks, as she gets reports of woe or non-woe from her friends and from the many arriving B&B guests.

O2 is garbage here. We’re not sure about Vodafone, risky. Perhaps ok, perhaps not, as a friend might be using Voda in Heasta but Janet can’t remember for certain.

EE or Three are certainly the known good ones to go for here.

[meritez]

Ok,

I would consider picking up the ZTE mf286d, it's got a proper bridge mode, it's cat12, supports all the necessary 3 bands you require and is £45 from cex.

[Weaver]

Thanks, I will do so. Excellent. I read about the ZTE recently in a thread. Yay ! Bridge mode !

I get the feeling that I’m out of ideas with the SXT. Do we all agree?

If so, can I put the MikroTik SXT to some good use? I can of course return it to you, but that’s probably not what you want, as it may make little sense circling round to where we started. And me wasting your time for nearly a year, for which I sincerely apologise. Breast cancer, pre-existing major depression, and my own ill health played their part in wasting time.

[meritez]

@Weaver, you have not wasted my time, I hate seeing good technology go to waste.

It's designed for a rural connection.

Put it for sale in the for sale forum and donate the money to Kitz website for running costs if you want.

[Weaver]

Have ordered that (unlocked) ZTE from CEX.

[meritez]

Have ordered that (unlocked) ZTE from CEX.

Good, it's £69.99 from Amazon, but I do not see any reason to pay more than £45:
https://www.amazon.co.uk/MF286D-600mbps-External-Antennas-Renewed/dp/B09HHJHFL2

[meritez]

https://www.youtube.com/watch?v=sVjSlpWnE-8