I'm sorry to ask such a stupid question. I have absolutely no tech knowledge and don't understand a lot about the router, access point etc. business.

Short version: I can only ever successfully get a connection on two of my 3 devices, doesn't matter which of the two. Does this have to do with what type of product (aka an access point or router or whichever this counts as) I'm using? 
Long version:

In my university dormitory there is only an Ethernet access. So my father bought me this travel router/access point thing to connect all my devices (one laptop, one iPhone and one iPad) to the internet. It might be worth noting that I have to login via a lock-and-key website each time before I can really access the university net, so I've already had tons of trouble trying to make sure I always have the right type of IP-address (something about how it has to belong to the network provider of this uni net or something?).

But just now I noticed that I can only ever get access on two devices at once? When I'm connected on my laptop and my phone, then my iPad will always get an IP-address that makes absolutely zero sense, so nothing works on there. And this morning I was able to connect on my phone and my iPad, but my laptop wasn't able to connect anymore. And I wasn't even able to open the tplinkwifi.net, as if I wasn't even recognized to be accessing from a tplink product anymore. 
 

Is this because it's an access point or something? Can it only provide a connection to a limited amount of devices at once? I just don't know what I'm doing wrong...

Best regards!