How do I get control over what my network configuration does?

[Churys]

Two days ago in the evening, my computer that always used network 2 made a network 3 that included the neighbor's computer and there was extreme lag.

Even after they're gone, there's still some lag, and whether network 2 or 3 is active varies per start up. The way the network looks keeps changing randomly across the night :

Sometimes it can't detect them at all :

This next one is closest to how it used to be, except without the question mark, having a tower instead :

Currently it is this the third one down again.

Several of these have the modem type also listed at the bottom of the page as hardware it can't identify.

The BRCM one is the only one I can click to get to the normal IP adres of the modem.

I can't access the IP address of the others, which leads to this :

I suspect I've been hacked, which would explain the lagging in the evening. What I don't get is why the network keeps changing, and what I can do about any of this.

 

[MilesAhead]

This looks helpful
How to Secure Your Wireless Home Network: 8 Steps (with Pictures)

 

[Churys]

Thank you, but does this also work for systems that aren't wireless? My computer is connected with a cable to the modem through the electrical network. The example in the link shows a network centrum that displays all homegroups, while mine only displays the active one. How can I get it to display all? I can't find an option to change the network name.

 

[MilesAhead]

This is in all the books on networking. But I never ran into anyone who actually used this technique. Maybe there's a network pro reading who has some insight?