I have been struggling with this for some days now and I am out of ideas. I just moved into a new apartment (rental) where the internet is shared between the different apartments.
The structure is: a modem/router acts as gateway and as a DHCP server. The router is connected to a 8 port TP-Link switch. From the router, 3 cables go towards apartments, one goes into the switch, and from the switch 3 more cables go towards apartments. One of the cables that leaves the switch ends up in my apartment.
The Wireless connections
The wireless connection to the modem/router is quite weak. In general, it works (ping 10-15ms), but every 15 minutes or so it stops working and a disconnect-reconnect usually does the job. Sometimes, it does not work at all. I couldn't really diagnose why, but:
- the router/modem has an address of 192.168.178.1, and assigns IPs between 192.168.178.10-192.168.178.72.
- sometimes when I connect to the same SSID, the laptops connect to a different router, with an address of 192.168.0.1, that assigns 192.168.0.100-192.168.0.199. When this happens, the internet barely works. Sometimes, no websites work, sometimes, only a few do (such as Google or Facebook).
- when I am connected to this router, I can access the configuration page. It is set on default settings: DHCP, it tries to gets its address from a DHCP with "dynamic IP". However, it shows WAN port is unplugged!, and no WAN IP address. It also has its own SSID! And I can also see the password in the configuration.
- when I connect to the SSID of the mystery router, I can access Google / Facebook but nothing else.
- On a Windows laptop, for some reason it usually connects to the mystery router. Sometimes there is no IPv4 internet connectivity, sometimes there is no IPv6 connectivity, most of the times neither.
- Finally, on the configuration page of the main router/modem, the mystery router is nowhere to be found.
The wired connections
Trying the end of the cable that goes into my apartment, and things went fine. I bought a cheap TP Link router (same model as the mystery router, by coincidence, different MAC), that I plugged in, it got an IP via DHCP and worked very well for about 2 weeks. Restarted it once or twice during this time.
For a number of days now, it shows no connectivity from the WAN cable. Also a laptop directly fails to get any IP address from the cable connection.
- Connecting the laptop directly to the cable that goes from modem/router to the switch, internet works fine.
- Connecting the laptop by cable to the switch, the laptop does not receive any IP address.
- If I plug in the laptop in the cable in my apartment, it does not appear as a device in the configuration page of the main modem/router. The laptop fails to get an IP address via DHCP.
- If I manually configure the IPv4 on my laptop (I give it an IP 192.168.178.5 / default gateway 192.168.178.1), then there still is no internet connection, but the device appears in the configuration page of the main router/modem as connected (but not "active").
- The switch has green lights that are on when there is a connection and blink when there is traffic. For the cable that comes from the modem/router: blinking; another cable there: blinking; the cable that goes to my router (or to my laptop): just on.
Ideally, I want to have my own router in my own apartment (as it was for two glorious weeks). Problem is that the rental agency is clueless about network things, while the ISP doesn't really care about some complicated network configuration as long as the router/modem that they provide works.