Alcatel Link Key Modem & MR3420 Router Configuration with Orange Internet Contract

Hello. A few days ago, my grandfather signed an internet contract with orange (20GB / month, 5mb / s, 40 PLN / month). He got an Alcatel link key modem, but because he wanted to have wireless internet, I brought my old router - mr3420. I tried to configure it to work in conjunction with the above-mentioned modem, but there is still no Internet access: / The LED on the modem is red, which means that it is connected to the LTE network. I would like to add that in the modem settings I cannot turn off the automatic PIN code checking. Please help!

Good advice, let grandpa resign from this contract if he can. He made it on terrible terms with the worst possible equipment. Nobody who has a bit of a clue takes this offer Orange with such scrap, this modem is worth PLN 0 and my grandfather probably sold it from inventory-excavations. They haven't been offering it for a long time, Alcatel hardware is not compatible with most routers, including the MR-3420. In Orange, the offer includes LTE Internet for the home for 59.90 150 + 70GB, overnight nights and only MF286 for PLN 0. This is a router with LTE-A worth PLN 500-600. Where does grandpa want to use LTE mobile internet?

I told him the same as soon as I saw the invoices ... He wanted to give grandma a birthday present, but it probably didn't work out well for him, because he got into a total mess. The more so that he soon ends his contract with the digital Polish and he can take internet + TV, even for PLN 85: / I don't know how to tell him because he'll probably be offended, eh ...
As for the uses of this internet - web browsing and possibly Skype.