iMac can not see wifi home connection but it finds others

I have an iMac whose wifi connection has always worked very well. Now that I moved in a shared house with a shared wifi internet, the iMac is not able to see our own wifi network, but it is able to see other wifi networks in the vicinity.

I have another laptop with ubuntu installed, and that is able to see the network and to connect, from the same room where the iMac is.

I have tried to make a new connection with the name and password of the network (which I know for sure because they are the same used on the ubuntu connection) but it does not appear in the network list.

I have tried to read more on the internet, but all the thread are related to connections which can not be accessed, while in my case the iMac can not even see the network.

Any advice? I do not knwo what kind of details are needed to define this case, but I will be happy to furnish any necessary data.