No train Cochem to Koblenz?

Bahn.de (or .com) = DB, the company that runs most of the trains in Germany.

Omni = 3rd party site selling train tickets.

I don't know Omni. Not snarky, I've just never heard of them.

Deutsche Bahn run the trains, maintain the tracks and operate the stations. They know what they are talking about.

Of course there are trains - Cochem is on the way between Trier and Koblenz.

One just left. It was on time, due to arrive Koblenz one minute late.

It goes at xx:18 and takes 38 or 39 minutes, and at xx:44 and takes 52 minutes. Even though the slow train is 14 minutes slower, you can just take which is convenient.

The slow train stops at every anthill between Trier where it starts and Koblenz where it terminates.

The fast train comes partly from Luxembourg and partly from Mannheim, they join in Trier and it only stops at express stops. It too terminates at Koblenz.

Omni? Do you mean Omio (www.omio.com)? Omio doesn't show a train between Cochem and Koblenz, although it does show trains between Trier and Koblenz, which stop in Cochem. Go figure!

1. As Badger says, they are a 3rd party seller and do not sell tickets for every route the Bahn has. Specifically, I found connections on smaller rail lines that were shown on the Bahn website but were not offered on Omio. Or connections to smaller towns on a main line were not sold by Omio when connections between major towns were sold on Omio, like Cochem to Koblenz. Also, Omio has almost no bus connections when the Bahn shows many.

2. For routes on which they do sell tickets online, they appear to be a little more expensive than the Bahn.

Except for getting an advance purchase discounted ticket, there is almost no other reason¹ for buying Bahn tickets online, in advance. Occasionally I purchase an advance purchase ticket directly from the Bahn, but mostly I use the Bahn website for planning purposes (train times and fares). Omio is almost worthless for planning.

1. Once I was flying into FRA and I wanted to go by ICE to Karlsruhe Bhf (and on to Bad Wildbad). There was a connection leaving the Fernbahnhof just after my scheduled arrival, which I knew I could not make unless the plane was early, and then probably only if I didn't have to stop to buy tickets. So I made an advance purchase, at full fare, of a ticket that would allow me to just jump on the train without buying a ticket and that I could use for the same price on any later train.

There is no need to book this train in advance, as it is just a regional train. The Bahn.com website shows that Cochem to Koblenz is a local network ticket, bought from the VRM (Verkehrsverbund Rhein Mosel). There will be a vending machine on the platform that sells tickets. Click on the "to selected offers" button and you'll see it is 12.40 EUR for a single one-way ticket (Einzelfahrschein), or there are a variety of day ticket options. If there are 2 to 5 of you and it is after 9 am (weekdays, anytime weekends) you can buy a small group day ticket (minigruppentageskarte) for 24 EUR and get unlimited train and bus travel in the district for the rest of the day.

Bahn.com is also the most complete source for other European train schedules, if you need them, most published for travel dates through Dec. 12.

I just checked Bahn.com, and they now (as if today) have travel schedules and ticket purchasing through Dec '21.

OMIO used to be Go Euro. They changed the name last year with the goal of expanding their ticketing app worldwide. Just in time for the pandemic to strike. The idea is to provide seamless travel ticketing through their app across multiple transport modes. The app seems to have hit a snag here. While I'm sure it has a link to Deutsche Bahn ticketing, it is not interlinked with the plethora of German Verkehrsverbunden.

These are area transport authorities that unite the various local transport operators into regional networks with a unified pricing structure and ticketing. Since the local networks now pay for the operation, they have insisted that transport tickets for travel wholly within their district borders can only be bought from them. Thus, even though the regional trains that run between Cochem and Koblenz are red with the "DB" logo, and the train personnel are DB employees, DB can't sell you a ticket. That has to be from the VRM, who pays DB to run the train. OMIO apparently has no link to the VRM, so they can't sell you a ticket (or earn a commission from that sale), so as far they are concerned, the trains don't exist.

Germany has dozens of these transport networks, covering virtually the entire country. I am thinking it started about 5 years ago that DB stopped selling tickets for local networks. At least they will tell you the name of the transport network, and if you click through they will show you a variety of pricing options. Usually there are very good deals for unlimited travel for the day, or several days, for individuals, or for groups of 2 to 5 passengers and families.

Net net, nothing beats local knowledge of how things work. Lee is the master, at least Stateside. There are Germans who visit this site whose knowledge is encyclopedic. So while a universal travel app on your smart phone is a traveler's dream, it is still a long way from being a reality.

I've never had any trouble buying a verkehrsverbund ticket or day ticket through the DB app. Munich, Nuremberg, Stuttgart, Frankfurt and many others. I do prefer to use the local apps for the best overview of the honeycomb and other options, but my payment is usually through the DB app.

World of difference between the OMIO app and the DB app. Can you buy British train tickets with the DB app?

No, you can't because there are no through trains from Germany to the UK. Situations like that are where apps like Omio, trainline or loco2 come into play, which offer to book trains of different national railroad carriers for a single connection, e.g. Munich - Vienna / Vienna - Krakow. However, that can become a trap as soon as the second ticket is train specific and you miss the connection. Then the second ticket is (often) worthless, because the apps do nothing else but combine two separate tickets that are subject to different tariff conditions. Caveat emptor.

it [Omio] is not interlinked with the plethora of German Verkehrsverbunden.

They wouldn't get a commission by them, so no incentive to do so; same holds for Laender tickets.

BTW, Omio usually has a small markup on the fare. E.g. my preferred morning train (dep. 9:55) from Augsburg to Nürnberg is €17.50 saver fare next monday while Omio offers it for €18.

Actually, SLA, Omio also offers that ticket for 17,50€ (it just rounds it to 18 on the board with all the options). But then they add a 1€ service fee for 18,50€.

As for Länder-Tickets, if you put in Munich to Salzburg for 5 people, Omio offers a 56€ fare (53€ for a 5P Bayern-Ticket plus a 3€ service fee), but they don't know about the Meridian Guten Tag Ticket (valid only on Meridian trains, which are almost all, if not all, regional trains between Munich and Salzburg), 50€ for 5 people. But the Bahn website won't offer the Guten Tag Ticket, either.