USB dongle for a router, for FTTP backup - Page 1
Forum section: electronics / general

author: peter-h
author_rank: Super Contributor
timestamp: October 01, 2024, 01:40:45 pm
content: For years I've had a Draytek 2955 and now a 2960 as the main "ADSL router" for the office.This does PPPOE and thus supports ADSL modems, and FTTP, directly.This also has an USB port with an automatic failover to a "3G dongle", so far an MF100. It uses it as a PPP modem, with the usual ATDT*99#. There is also a "4G DHCP" optionbut I never managed to get this to work, with some boxes like a TRB140. I think that can do a router but not a "PPP modem".The ISP (Andrews & Arnold, a "business" ISP) has sent out a new SIM card but really anything more they say is not their problem. Their system, when it works, re-maps your IP block to this dongle when the PPPOE fails. And this used to work perfectly until just recently.A small detail is that years ago they misconfigured their system to remap only the 1st IP from the block but it still gives us a basic internet access, and they have not been able to fix it, so on the failover we lose our VOIP phone systemProblem: the UK has dropped 3G, the MF100 does not do 4G, and Draytek (some chinese guy) is telling me you cannot have 4G over USB! I reckon this is BS - the router end ends at the *99# dial-up and after that the dongle can do what it likes.Or am I wrong?I bought a few 4G dongles on Ebay for ~£10 each and will see if any of them work.We do need this 4G backup because the FTTP fibre links do get damaged from time to time.I've got this dongle list from Draytek and some of them clearly do 4GI have almost no idea what the "4G DHCP" mode is. It is still something running over USB, apparently. I sort of know that DHCP is what an ISP gives you - even with a "fixed IP" they config their router to always issue you with the same IP. So maybe that is what 4G DHCP is.

author: Nominal Animal
author_rank: Super Contributor
timestamp: October 01, 2024, 07:58:09 pm
content: (I wrote two way too long explanations of the relevant tech and my background, but then realized you don't need/want to know, and are instead interested in solutions that should simply provide you with the service. Hopefully, this is an improvement over those, and not too long!)Pick a 4G/5G/LTE USB modem supported by both the Vigor2960 andThree UKfor your exact location. (You are buying services from A&A that subcontracts Three UK for the 4G connection, according tohere. That is the only reason; you don't need to buy anything from Three UK.)Make sure your contract with A&A includes the backup support, and you have a data SIM from A&A. That SIM will be used with the new modem, just like in your old modem.In the Vigor2960 configuration, you use default settings, with your username and password filled into the PPP username and PPP password fields. A&A needs those to be able to update IP routing to use the backup connection; it will not work without those. (This, too, is explainedhere, near the bottom of the page, when you click on theTechnical details.)

author: peter-h
author_rank: Super Contributor
timestamp: October 01, 2024, 08:42:21 pm
content: The long versions would have been interesting tooI go back to the modem days, 1200/75, and have played around with this stuff. ATDT*99# gets you a TCP/IP connection and you need to then connect the serial port to your TCP/IP stack and then off it goes... you have "internet access" from the ISP. Never played with "4G/DHCP" although I know DHCP. Actually I am sure you can run a serial PPP connection to a USB dongle over GPRS 3G 4G and presumably 5G too. Just not at USB FS speeds but more like USB VCP (CDC) speeds which are still ok - hundreds of kbytes/sec on the arm32 product I've just developed.Anyway I've bought an E3272 on Ebay and will give it a go.There was never a username/pwd configured, over the 10+ years I've had this backup system running via A&A! I can only assume they have set up the SIM card to send some kind of ID which ties it to my firm's ADSL service.

author: Nominal Animal
author_rank: Super Contributor
timestamp: October 01, 2024, 10:03:27 pm
content: Quote from: peter-h on October 01, 2024, 08:42:21 pmUSB CDC uses the control endpoint and specific USB messages for the AT commands; only data goes over the bulk endpoint.Quote from: peter-h on October 01, 2024, 08:42:21 pmI've used 3G/4G/LTE for almost a decade for internet connectivity at my mom's house, north of the Arctic Circle. I don't use USB dongles anymore, as they really are just tiny Linux servers stuffed inside those tiny USB sticks that handle the connection and use Linux USB Gadget drivers for the USB connection to the host. Many of them expose an USB mass media device by default, and require so called "mode switch" – USB configuration change – to expose the MBIM/QMI/RNDIS/ethernet interface.Funnily enough, the plain miniPCIe modems tend to be more expensive than the full USB 4G/LTE dongles.For testing, I use cheap (<10€) USB WWAN miniPCIe adapters with SIM card slot. Most of these are not suitable for long term use, because of excess heat generated by the USB 4.5V-5.5V to 3.2-4.2V conversion at the occasionally high currents. MiniPCIe 3G/4G/LTE modules – I have Huawei ME909s-120 and a Mikrotik R11e – are actualmodems, with only specific pins on the miniPCIe connector used: 3.2V-4.2V on pins 2, 24, and 52; GND on pins 9, 35, 43; SIM socket on pins 8, 10, 12, 14, 16; and USB 2.0 (HS) on pins 36 (D-) and 38 (D+). Newer modules may also support USB SuperSpeed on pins 23 (TX-), 25 (TX+), 31 (RX-), and 33 (RX+). The modules do not contain a SIM card slot, it must be external.The miniPCIe 3G/4G/LTE modules implement an USB interface using standard CDC protocols (some subset of Ethernet, MBIM, QMI, RNDIS), so the adapter has no logic at all in it; the adapter only has DC conversion and connectors. The miniPCIe modules have typically at least two connectors for suitable antennae; mine have IPEX MHF aka u.FL connectors which I connect via "pigtails" to standard SMA connectors.Best ones have a high-efficiency 4.5V-5.5V to 3.8V switchmode DC-DC converter (with low generated EMI, on the other side of the board vs. the modem, and a full continuous ground plane in between) and a suitable level translator like NXP NVT4555UK, since SIM cards really want 1.8V or 3.0V and the radios work best at 3.8V. I've even considered making my own, because of this. 4G/LTE -enabled routers have this built-in, and it obviously isn't expensive; at least HP has some corporate laptop models with a similar slot.The ones with linear regulators do work absolutely fine, but generate too much heat to be comfortable in continuous use, at least with the kind of radio transmit powers I see. Typically, the modules can draw somewhat over 1A continuously at maximum radio transmit power, but normally the draw is discontinuous/spiky/switchy, so the peak draws much higher. Early modules ones drew well over 2A peak, and needed excessive bulk capacitance – USB 2.0 only allows 10µF on the device side – to work well.These modules really can do about 350 Mbit/s over USB HS. Mine are LTE Cat4 (which supports up to 150 Mbits/s down and 50 Mbits/s up) or Cat6 (which supports up to 300 Mbits/s down and 50 Mbits/s up). All within USB HS capabilities, so no problem there; the practical rates depend on the ISP and the radio connection –– in my case, especially on the antennae I use.The ones using USB SuperSpeed can do up to gigabits per second, of course, so are only limited by their radios and own hardware.I also have a MikrotikRBM33G(bare router), running OpenWRT, that can take two miniPCIe modules. While it is a "weak" SoC, it is well suited for this kind of stuff, and can even do IPsec tunnels at reasonable 4G/LTE bandwidths. Using OpenWRT and at least one 4G/LTE module, it becomes a 4G/LTE router with three 1GbE ports. One of my long-term hobby projects is to find out how to make a small user interface – 2.8" or so TFT and capacitive touch, plus maybe a couple of buttons – that allows non-technical users to check the connection status and understand what the problem is when the connection is down, without having to understand anything technical, or being able to stop or misconfigure or otherwise mess the device from the physical UI. (Because of the latter, I'm currently using a Teensy 4 for the UI, connected via USB to the RBM33G. This also makes it independent, and suitable for any other OpenWRT router.)Quote from: peter-h on October 01, 2024, 08:42:21 pmI don't see why the device wishes to distinguish between 3G and 4G. This setting should work exactly like the 3G option, AFAICT. The DHCP obviously refers to the internet-visible VPN endpoints getting a dynamic IP address, but that should be perfectly okay as it doesn't affect your connections any.Quote from: peter-h on October 01, 2024, 08:42:21 pmAs long as it is not carrier-locked, it should work fine for you.Note that you can trivially test it by getting a "consumer" data SIM (for laptops and such), and putting that in the E3272, and sticking the USB stick to your computer. Doesn't matter if it runs Windows, OS X, Android, or Linux (graphical desktop), they all should detect and prompt you with a window asking the wireless ISP settings. Here in Finland, it suffices to select the vendor; everything else are default settings. Sometimes a PIN is used.Same thing my FrankenModems, the 4G/LTE miniPCIe modules on an USB WWAN miniPCIe carrier with a SIM slot.

author: 5U4GB
author_rank: Super Contributor
timestamp: October 02, 2024, 09:14:58 am
content: I think you're approaching this from slightly the wrong angle, don't use the Draytek as your bridge via a USB dongle but use some external device connected to one of the Draytek's WAN ports. I eBayed a used Robustel 4G modem and used that, but you can also get a range of new ones from Aliexpress for about the same price. That way you're just talking to another device over ethernet rather than trying to get a specific USB dongle working with the Draytek.

author: peter-h
author_rank: Super Contributor
timestamp: October 02, 2024, 11:06:35 am
content: I am sure you are right. I did spend some time on that too, with 4G boxes like a Teltonica TRB140, without success. They have so much config (they are linux boxes basically) and I could not work it out. I did get it working for internet access for a laptop though.Another thing is that the Draytek routers do automatic failover to the USB dongle but I can't see how they can do that for an ETH connected 4G router.

author: 5U4GB
author_rank: Super Contributor
timestamp: October 03, 2024, 04:27:12 am
content: Looking at the TRB140 web page it seems like overkill, it mentions DNP3 and modbus which implies there's a lot of functionality and configurability in there that you probably don't need. With the Robustel it's just a case of dropping the SIM in, making sure "Automatic APN Selection" is checked, and setting the IP address and you're done.For the failover, you should be able to set the Active Mode for your primary WAN to Failover and then select the alternate WANs you want to fail over to, that's a neat feature that Draytek's have had pretty much forever.

author: peter-h
author_rank: Super Contributor
timestamp: October 03, 2024, 04:11:58 pm
content: Do you mean this one:https://www.ebay.co.uk/itm/226373012849?A&A (the FTTP ISP, and the ISP providing the SIM card) say that the networks have tightened up the SIM card expiry and now you need to go online (basically, break the FTTP to force a failover to 4G) once a month or so.This is stupid, in a corporate environment where somebody needs to be assigned to do that test, picking a time when nobody is online...

author: 5U4GB
author_rank: Super Contributor
timestamp: October 04, 2024, 08:42:53 am
content: That looks like way overkill, I got a second-hand R2000 for something like USD25. It doesn't have to be a Robustel, there's a variety of different vendors products available second-hand.For the SIM, I used aKeepGo data-only SIM, this has the advantage that you only pay for the data you use so best-case with very infrequent failover you can pay something like USD3 per year for the minimal top-up after the initial purchase which gives you something like 3GB. For other setups I just got the cheapest prepay SIM I could find, you typically have to activate it on a phone but once that's done you can move it to something else and use it there. There are some that are even specifically advertised as fine for tethering, which is in effect what you're doing.

author: peter-h
author_rank: Super Contributor
timestamp: October 07, 2024, 12:05:11 pm
content: I am happy to report that this E3272https://www.ebay.co.uk/itm/145804607846is working fine as the 4G backup, with the A&A supplied SIM.The old issue remains i.e. they are still not rerouting the whole IP bundle via this, so we get just one IP, so "outgoing" internet access only. This used to work years ago and then stopped and despite much communication they were never able to find anybody there who knew how to make it work. So our VOIP phones go dead, and any servers in the office (we still run a machine for testing stuff) are also inaccessible. But that is OK.I am using the PPP mode, not the "4G/DHCP" mode.

author: Postal2
author_rank: Frequent Contributor
timestamp: October 07, 2024, 01:14:03 pm
content: Quote from: peter-h on October 07, 2024, 12:05:11 pmI have one of these lying around (4G LTE). But not a dongle.

author: peter-h
author_rank: Super Contributor
timestamp: October 07, 2024, 02:46:16 pm
content: I don't think that would solve it. It is the configuration of the Andrews & Arnold routers that decides how the IP block we own gets mapped to the 4G service when the FTTP to 4G failover happens.

author: Postal2
author_rank: Frequent Contributor
timestamp: October 07, 2024, 03:30:29 pm
content: Quote from: peter-h on October 07, 2024, 02:46:16 pmI agree. But this old device is 3 times cheaper than a USB dongle, or is given for free. And it works with 4G.