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Forum Index : Microcontroller and PC projects : LINUX MINT 22.2 - Will not let me have TWO network connections...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9698 |
This one is interesting.  I can use the WiFi just great for all my Internet - works perfectly. But as soon as I configure the ETHERNET port with a static IP address, the WiFi is automatically disabled - so my intenet access stops. It's like Mint is now ASSUMING that the internet is now via the Ethernet, which it ISN'T. DISABLE the Ethernet, and the internet springs back into life. Very strange. But try to enable BOTH the Ethernet with static IP, AND the WiFi, and nothing works. Not the Ethernet, not the WiFi. Anyone seen this? I have a server running on a 192.168.x.x IP4 address, and this server AND this network is NOT connected to the Internet in any way - it is totally LAN. But at least I am on-line with my new Mint machine now, so I will just leave the LAN disabled for now, so that I at least have access to the net.  EDIT: Mint is pretty amazing, I have to say. I have a whole heap of webpages open in Opera, and the RAM consumption is only 4.5GB out of 16GB installed. ZERO bytes used in the swap file. In W10, about the same number of internet tabs open, was running around 12-16GB out of 32GB installed. Yes, naturally some OS overhead there, but I'm pretty impressed with LMDE6 so far. Sure, I have some glitches to work out, but for the most part....  Edited 2025-10-17 16:38 by Grogster Smoke makes things work. When the smoke gets out, it stops! |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 8212 |
I doubt if most people would consider that to be a problem. I'm not sure if anything will do it, in fact, as it's something I've never tried. Your PC can only have a single IP address, can't it? I'm not that hot on networks. We use NAT WiFi hubs so the external network can't see internal network addresses unless a DMZ is set up on the hub. That makes it safe to have any internal servers in the same address zone. There's no need to have servers on 192.168.x.x as the external network simply can't see them. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9698 |
Yeah, but this is a LAN - an INTERNAL network. This network consists of just three machines, all via a switch, but totally isolated from the WAN. There is no physical connection between the LAN and the WAN. The LAN machines are all setup with static IP's, so THEY can talk to each other, but NOT the internet(none of them have a gateway IP). This is by design, as the server is only local to the LAN, and is NOT allowed WAN access. It is only for my mediaplayer, and for me to be able to copy new files to the server from a box that DOES have WAN access. When on W10, I simply setup a static IP on the Ethernet port for the LAN, and the WiFi did the WAN and internet. This kept them totally separate, if you see what I am getting at. Edited 2025-10-17 17:01 by Grogster Smoke makes things work. When the smoke gets out, it stops! |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4093 |
I'm guessing about intentions, but that might be what almost everyone would want and expect. It'll be to do with which (network) paths are even enabled ("up") and then what routes are set. If it worked in an earlier OS (Mint?) then I suppose all the settings are in it, (though maybe not via GUI) and could be used to tweak your new system. There may be posts on the net about others who have found the same and worked out how to do it. (Sorry, I've no equivalent set up, well, not Mint or GUI.) I'd say you want both interfaces up, the default route/gateway to the net and whatever should use the ethernet obviously has to use its IP (and if it's done via a name then a DNS etc that maps to that IP addr, maybe in /etc/hosts?). Thinking aloud... I'd do what you've got now (internet via WiFi and enabled as OS wants) and then resort to the command line unless you can find posts about this that aren't command line. (Umm, just realised my setup isn't the same as my PC just has ethernet, goes to router, then local LAN traffic goes to local and web etc goes via ISP's fibre, i.e. each PC has only one place all traffic goes and the router does the rest. Oh, it's a bit more complex as I've a DMZ and extra routers... Anyway not same as yours, sorry.) John Edited 2025-10-17 17:17 by JohnS |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9698 |
Here is a snapshot of the issue... .png) With Ethernet disabled, everything is fine. ENABLE it, and BOTH the WiFi and the Ethernet stop working. Might post about this on the Mint forums also, cos this does seem very odd... EDIT: Yes, I think you - and Mick - are correct. It's just I am trying to access two networks at once from one machine. @ Mick: Yes, you can have several different IP addresses on any ONE machine, so long as you have MORE then ONE network adapter. Assuming you have two(or three in my case), you can have two(or three) separate IP addresses on the same machine - one for each of the network adapters. Edited 2025-10-17 17:43 by Grogster Smoke makes things work. When the smoke gets out, it stops! |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 615 |
Sounds like and could be a routing issue. Open a terminal and check with netstat -r ipconfig -a your setting once you have internet access and compare it to the ones you have when both are connected and fails. Look where the default route points to and check, if router and server are really on the same network. Check the netmask and try to ping the router and your server in all situations. |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4093 |
Would be worth doing those on a working setup first, if you can. John Edited 2025-10-17 18:56 by JohnS |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9698 |
Awesome, thanks very much - I will try this tomorrow. Enjoying a few beers tonight, cos I have moved to Linux Mint and everything is just WORKING.  REALLY enjoying learning all about it, from the Windoze addict that I am. Just tonight learned how to make "Shortcuts" to the Mint desktop - that they call "Launchers". Dead easy, and all went flawlessly for the Linux apps. This is for things like GFXterm and MMEDIT, which DON'T show up in the main Mint menu - until you set it up and then the process asks if you want links in the menu under OTHER. I think I am now fully in love with Linux Mint...  Smoke makes things work. When the smoke gets out, it stops! |
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| dddns Guru Joined: 20/09/2024 Location: GermanyPosts: 615 |
Best success! Windows is so long ago for me but this ipconfig got hammered in my head. For Linux that's wrong..better try this: ifconfig -a The Lan network (always) gets the first place in routing table where traffic goes. If you connect your Wifi and both connections are via DHCP configured, it will keep the Lan as default even though your Wifi offers another default route. The Lan will be prioritized IIRC |
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| Andy-g0poy Regular Member  Joined: 07/03/2023 Location: United KingdomPosts: 80 |
It will come down to routing and such like. The network switching in the top level network manager is fairly simplistic a+nd usually assumes that you will have one network live at any one time, and if you activate another interface that will be the one to use. Static IP is irrelevant is all the same to the network drives if it's dhcp assigned or not. I assume that what you have is a local network on wired ethernet one one network say 192.168.10.0 and a wifi network on 192.168.11.0. These are two separate networks on separate interfaces, and by default they will NOT talk to each other. You can add various routes to direct the traffic destined for the outside world (internet) to go via the wifi network. Another option which is often automatically set up is to form a bridge between the two networks, which allows each network to "see" the other, in that case the default route will normally be set to the interface connected to the interface that provides the external internet access. As an asside, you can have as many networks as you want on a physical interface, so on the local ethernet you could have 192.168.10.0, 192.168.12.0, and 192.168.14.0 They will happily co-exist. This is known as multinetting, and is very frowned upon generally as it opens up all sorts of security issues, however it is very useful in the case where you need to move a entire network to another IP range, but keep everything running while you do so. As you only have a few machines, I suspect that the simplest solution will be to add a route from the wired ethernet network to divert all non local traffic to the wifi interface. Set the default gateway on the ethernet to the wifi ip and that should do the job. That should make the ethernet divert traffic to anything other than it's local network to the wifi network. There is a routes buton in network manager on the bottom of the IPV4 tab (I'm assuming that mint is using the same GUI system as Debian...) if not it should be fairly obvious or googlable :-) Andy |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9698 |
Yes, that is it EXACTLY. The WiFi talks to the router, which is conneted to the fiber, so that is the path to the internet. The Ethernet port is connected to a totally physically seperate network switch. Also plugged into that switch, is my mediaplayer PC and the server. The mediaplayer and the server cannot see the internet at all, only each other on static IP addresses. My main work PC(this one) has access to the internet via the WiFi, but also access to the private LAN network via one of the two available Ethernet ports. Internet has priority, so that is why I have just disabled the Ethernet connection - for now - that way, the internet works on my main work PC. I just can't access the server for now, but that was only sporadically anyway, when I wanted to copy some video or music files to it, so it's not super-urgent, but something I need to get fixed - eventually. I'll look into running those commands and comparing, but I think the members are correct about it being a Mint routing issue. As soon as Mint sees the Ethernet is active, it tries to get the internet via it - which will NEVER work, as that LAN has no physical(or wireless) connection back to the fiber+router. But on the plus side, everything else is working! Even signed back into my email accounts and YouTube etc all on the Mint box now. This is just a wee hiccup, which will get sorted at some point!  Smoke makes things work. When the smoke gets out, it stops! |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8212 |
Could you simply put everything on the same network and not enable internet access on the devices that shouldn't have it? It might be possible to do that in the WiFi hub, possibly by locking out devices by IP address group.It would simplify the hardware a lot. :) On my new hub you can time restrict internet access by IP address, so you could simply never allow certain IPs. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4093 |
I think if you get enough details from the older system that worked, and then see what's different on the non-working one, there's a good chance the new one can be made to work. Please check there's nothing in the old /etc/hosts more than the new /etc/hosts (as well as the netstat & ifconfig). It's the kernel, not Mint, we need to tweak (unless it turns out that the newer Mint does have a setting so far overlooked). Please give an example or two of how on the old system you used to access the things now inaccessible. (I'm guessing not scp, ssh or rsync, so what?) Say an inaccessible thing is on 192.168.2.123, did ping 192.168.2.123 used to work? And now does not? (Things don't have to allow ping, though.) John Edited 2025-10-18 17:04 by JohnS |
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