What does "Train has become lost" message mean? The train goes to a depot, gets a delivery, but then an alert shows up saying "train has been lost" and it's switched to manual mode. If I switch it back to automatic, it immediately "gets lost" again and goes back in manual, forever staying in the depot.

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For one reason or another the train is unable to complete the delivery. I've had the "Train Has Become Lost" message trigger when my trains were experiencing no-path errors, and one time I had a train constantly trying to pick up Electronic Circuits from a station that it had just delivered Electronic Circuits to (which I resolved by ensuring the station was set to "Request Only." You'd have to examine just what is preventing the train from carrying out its orders in your particular setup.

Looks like the problem was that I had set the network on the supplier to A1, but the requester just had A (I thought that meant it would take from all A networks, but apparently it's the opposite). As soon as I set requester to A1 and switched the train to auto, it went on its way.

However I think it is still a bug for several reasons:
1. The train still gets a schedule, just an incomplete one (only station names, no waypoints), which is confusing.
2. The "train has become lost" error message is misleading (the train is fine, there just aren't any deliveries to be made since requester and provider are on different networks).
3. The train gets set to "manual", which means even after fixing the stations, you have to find and click on it to make it move again (very fun if you have 10s or 100s of trains).
4. The fact that a network signal without any subnet mask counts as "sub-network 0" instead of "all subnetworks" is, in my opinion, backwards. It should be the other way around, or at least a setting that you can toggle.

How did you name a network "A1," with a combinator? The Cybernetic Combinators only have one signal you can set as a network name, so just curious if I'm understanding things right.

1. If I saw that, I would just assume that that's part of the breakage the error message is trying to draw my attention to.
2. I'm not convinced the error message is misleading; the train is lost because of incomplete or missing instructions when the train is expecting instructions. The message, to my understanding, is meant to cover a range of possible errors: "For one reason or another this train is being assigned a delivery it cannot fulfill."
3. Would it be preferable if the train went on its merry way with a messed-up schedule, possibly taking cargo to somewhere undesired and potentially leaving you to hunt it down in order to manually fix it? Perhaps a better solution would be to have it path to a depot and reset everything, though.
4. For someone like me who never got the hang of LTN-style network masks, it's far more intuitive to assume that, by default, differently-named networks are separate to each other, and that network names are simply names unconnected to each other (which I'm fairly sure is the default with Cybersyn). An option would perhaps be best, like how most shooters have an "invert mouse" option.

The mod has clear and exact messages for other alerts, such as "failed to find a train to deliver from station X to Y". There could just as well be a "no provider stations found on the same network as requester X", or even no message at all — if the deliveries simply weren't happening (no schedules appeared on the trains), I would have concluded that stations aren't configured right and focused on them. The "lost" message, on the other hand, talks about the train having a problem, mentions the depot by name, and a schedule is set on the train with the right stations, clearly indicating that the delivery has been configured. All of that is misleading. I spent over 10 minutes trying different ways of reconstructing and reconfiguring the train and the depot, wondering if I'm doing something wrong or is it a bug, because that's where the alert said (and pointed on the map) the problem was — at the depot, with the train.

And yes, the train should remain at the depot, in automatic mode, with a cleared schedule. Misconfigured deliveries shouldn't be permanently taking trains out of the network if they're empty and at a depot.

It kind of looks like the delivery might be assigned to the train before the sub-networks are checked, which would explain the apparently correct schedule (just the stations) as well as the error (the train has a delivery and at the same time doesn't because it's between different networks).

To clarify, I will point out that several times when I've encountered that message, the train was NOT at a depot, which is why I suggested that it be explicitly told to path to a depot when the message is triggered. Even if it goes to the depot and then gets set to manual, it's a lot easier to find that way. One issue with that idea is that it might make it harder to figure out what went wrong, since the train is reset and removed from the context of whatever triggered the error.

I don't think 10 minutes is very long at all to be troubleshooting something in this game, but fair enough, it would be preferable for the error message to be more specific if possible. That extra info is interesting, maybe the mod author can weigh in on that.

Still curious to know how you named a network "A1," since I see no obvious way to do that. Oh, and I see there is indeed already an option in settings to change the default network mask to a value of your choosing; the default is set to -1.

To clarify, I will point out that several times when I've encountered that message, the train was NOT at a depot, which is why I suggested that it be explicitly told to path to a depot when the message is triggered.

All my issues with this error are with trains at depots. After further testing I've encountered even more weird stuff, for example, I can get any train that's "lost" to actually do the very delivery it failed, just by repeatedly clicking on the "go to station" arrow for the depot. I'll get a few "train lost" errors and then on the third or fifth try or so it will suddenly no longer be lost and go and deliver exactly what it's supposed. Except it will then keep delivering it even after the requester is overfilled, even if I disable the "don't return to depot" feature in the settings, so I don't know what's going on with that. I'll see if I can set up a reliable test scenario.

Still curious to know how you named a network "A1," since I see no obvious way to do that.

I followed the mod instructions: "In addition, if the combinator receives as input a signal of the same Id as its network signal Id, then the value of this signal will be interpreted as a bitmask to give 32 "sub-networks" to choose from"

Oh, and I see there is indeed already an option in settings to change the default network mask to a value of your choosing; the default is set to -1.

Yes, I just noticed that as well. Which means no number is supposed to mean "all networks", but I'm not sure if it works that way. I'll do more testing when I can.

Gotcha, thanks for the clarifications.

I will update the lost train alert to be more specific when it can. As for whether or not this is intentional behavior I will look into that and get back to you. The goal has always been to be much more strict than LTN about preventing bad deliveries in misconfigured networks, but at the same time the logic might be classifying something as misconfigured when it shouldn't be.

Another thing that I realized a bit later is that it might not have been a station misconfiguration issue at all, but rather some kind of schedule leftover or something. Because the schedule that the trains kept getting (and which kept making them "lost"), was still getting assigned even after the stations had their combinators deconstructed. And the trains kept getting assigned deliveries between stations that had no combinators on them (or had the dispatched from Rail Logistics Dispatcher mod instead, as I was testing both to see which one works best for me). That would explain why the trains got confused, since they were trying to go between stations without combinators.

I think this was a Space Exploration compat issue related reflecting back on this conversation. I am 95% certain it is fixed in the latest version but since I could never reproduce the exact issue myself I am not certain. Lost train alerts are now way more specific in the lastest version so hopefully if the issue does remain it is much easier to track down. Update me if there is still anything I need to fix or look into.