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Q  Modem muddles

I live in the US, and I had to upgrade my modem to one supporting DOCSIS 3.1 to access the faster speeds from my cable provider. I have two Linux Mint PCs and two Windows 10 PCs.  After changing modems, the Windows PCs would connect to the internet, but neither of the Linux PCs would. I tried two different modems: an Arris SB8200, and Netgear Nighthawk. I called support to my ISP, and the modem manufacturers, but nobody could help.  I was never able to get the internet to work, so I had to put the old modem back. After doing that, everything started working again. I kept the Arris modem, just in case someone could figure it out.

Larry

A Looking at the documentation for the Arris modem, it should work. The manufacturers state that Linux is supported, so this is likely to be a configuration issue. One point to bear in mind is that although the modem has two Ethernet ports, you can only use one of them unless your ISP is providing you with two IP addresses, because this is only a modem and not a router.

These devices usually use DHCP to assign an address to a connected computer and to provide it with routing details, so make sure your Linux systems are set up to use DHCP rather than statically assigned addresses. Then see what the system logs says about your attempts to connect. Check the modem is powered on and connected to the Internet, then open a terminal on Mint and run $ sudo journalctl -f

This will show your system log as added entries. Now connect the Ethernet cable to the computer and modem and watch the log output. It may help to maximise the terminal window to see as much as possible. This should display the attempt to set up a network connection and show where it’s failing, and hopefully give a clue as to what is causing it.

However, with four computers, you’d be better off with a router connected to the modem, then connect your computers to the router. That would mean they could all access the Internet at once with the added benefit that they can also communicate with one another, making file transfer between them much simpler. Many routers also include wireless connectivity. Even if you don’t use a laptop, this could save on data costs for your mobile phone.