I apologize for probably starting a topic that has been discussed over and over here but I feel I have reached a point where I won't be able to set up the network without the help of the community - so, please help!
A long story short: I've been using a 10.04 Ubuntu PC, it had (PPPоE) Internet connection and shared it with a Windows 7 netbook through a wi-fi card. I cannot recall how exactly I set this up (after reading so many forums) but I've set static ip and gateway in etc/network/interfaces for the PC. I also had to specify some of the wi-fi settings through "sudo iwconfig wlan0..." (essid, ad-hoc type etc.) every session, since I couldn't do it through Network Manager for some reason. The connection worked ok most of the time, but I couldn't set up protection for it, also when I attached to the PC my Windows smartphone I lost my Internet connection, and so on, so I decided to make it the right way.
I got a Zyxel Keenetic router, attached it to the Ubuntu PC through a cable, changed the gateway to 192.168.1.1, set up the MAC address for the router, the PPPoE and DHCP settings. Windows 7 immediately got on-line, Ubuntu couldn't.
I changed interfaces to
iface lo inet loopback
iface dsl-provider inet ppp
pre-up /sbin/ifconfig eth0 up # line maintained by pppoeconf
iface eth0 inet static
I tried setting up NM, it seemed to establish a wi-fi connection ('Auto' appeared before the essid name), but as soon as I detached the cable from the router, it lost the connection again, no ping. If I put the cable back and reboot, I can get on-line again, very low speed, though.
At this point I realized I messed things up so much I couldn't fix it without the community help. I don't even understand where to start from.
PS More stupid questions:
1. Who has priority over who? Network Manager or interfaces? If I change smth in interfaces, it doesn't appear in the NM settings and vice versa, so what has more priority for the system?
2. NM doesn't show my PPPoE connection - is this normal?
3. NM doesn't show my PC and router cable connection - is this normal?