My problem is the following: on the 192.168.1. * network I have 3 machines. I call them U1 (Ubuntu Desktop), US2 (Ubuntu Server), W1(Windows) and a router named R1 in 192.168.1.1. U1 makes and receives response of a ping from W1 and R1. US2 can ping OUTSIDE the local network (and to R1) but receives no responses from W1 or U1. U1 and W1, when they ping US2, they receive no response. All machines access the internet over R1. US2 is updated with "apt update" without any problem. I apologize for the inconvenience and if this topic is trivial, but I have run out of neurons and I have not found an answer. Thank you in advance for your help. (Google translator) I can't insert logs of US2 because he has only user interface within command line, not GUI.
23 Answers
Do you know that you can block or unblock ping requests in Ubuntu Server 20.04 LTS? Look at this article to know how:
Maybe it will help you
1This sounds like a netmask or route problem...
At the command prompt on US2 check the netmask. Do an 'ip a' and for the primary interface you should have 192.168.1.*/24
Then do an 'ip r' to get your routes. For a 192.168.1.* subnet it may have a bunch of other stuff in it but you should have:
default via 192.168.1.1 dev eno1 proto dhcp metric 100
192.168.1.0/24 dev eno1 proto kernel scope link src 192.168.1.1 metric 100 (Your device names may be different)
The default is clearly working if you can ping outside, and the next line is establishes the 'local' route on your network which is might be the issue.
Also if you've got any other lines with 192.168.1.* addresses in them that might mess things up. If you've got virtual machines running on US2, or Docker / containers sometimes you can accidentally configure an overlapping route that breaks things.
If your IP is set statically check then yml file in /etc/netplan/ to see that you have the /24 suffix on the main IP address of US2.
1Inexplicably, seeing "witches" everywhere, I have switched the ethernet cable from one port of the router to another and, miraculously, now it works! I can't find an explanation for this issue. I very much apologize to everyone who has tried to help me with the little data they had.
as far as I'm concerned, this topic should be "CLOSED".
