Internet access, hotspot, home network?

Following situation: I live recently in a flat which is supplied by means of EoC (Ethernet over Coax) with Internet. The property management has commissioned a small company to equip all the apartments of the house with EoC modems. Using a LAN cable you can then connect a router, PC, … With the modem. I currently have an access point in operation, which then provides me W-LAN.

My problem: The o.g. Company gives me my user access (username and password). With these credentials, each time I have to log onto their website, similar to a hotspot at a train station, and then I can use the Internet (Google, …).

Assuming I'm with the laptop on the web and would like at the same time with the smartphone to the Internet, the service throws out a device so that I can only use the Internet with one device.

An Amazon Echo can't be set up, since there's no sign-up website aufpoppt where I can enter my credentials of the company.

I've tried a lot, but with my knowledge, at the end.

My solution idea: I need a device, which fooled the company that I use a total of only one device, in which I enter my credentials once. This device then provides my end devices with W-LAN or LAN. Is there something to buy?

Info: The IP addresses are assigned by the company's DHCP server. I already tried a router as a solution and failed.

A private DSL box in the apartment is not feasible.

Would check with the company, whether other authentication methods other than calling a website are available.

Which provider is that?

Your solution idea is router. Nothing else does the common DSL router. Afterwards, he presents a MAC address and gets only one IP from public DHCP.
Internally, he acts as a DHCP server and provides (almost) unlimited clients.
He gets the conversion via Network Address Translation.

Your solution seems a bit more exotic. We should know what this is about. If necessary, a WLAN client / router can help the network to do just that. In hotels, I do something with the TPLINK 3020 as a wlan client occurs and then I hang on a LAN can to my local network.

There are 3 possible solutions:

Router. Or a router. Or a router. Nothing else.

There you enter your access data and you're done.