I did a vanilla installation of 20.04.1 LTS on a PC using a wired connection (no on board WiFi) to a Netgear Gigabit switch for LAN access using an RJ45 Cat6 data cable (checked for correct integrity) which in turn is connected to a 4G router for internet access. This is the only operating system on this PC.
I also have a Synology NAS connected to the same switch mounted in fstab which works perfectly fine. The NAS share (GnV_Common) is shown on the desktop using GNOME Extension Desktop Icons NG (DING).
This arrangement has worked fine and without issue in Ubuntu 18.04.5 LTS (the only difference being that the appearance of the NAS Share on the desktop is handled differently in 18.04)
I mention the NAS arrangement because, curiously, when the internet drops out, the NAS share disappears from the desktop too (Network Manager related perhaps).
There is no apparent trigger for this behaviour I can establish.
On a few occasions, I have noticed that there is no internet access on the 20.04.1 box but yet the Network Manager indicates that it is connected (image from last incident), and the Network Manager icon on the System Tray remains constant:
The issue was not repeated on the 18.04.5 box which continued to access the network and the internet.
My research has taken me (through many questions only related to WiFi issues) to this answer to a similar question
In this regard, the
managed=false flag is set. For comparison purposes, I also checked
NetworkManager.conf file in the 18.04.5 LTS box and it is set the same way so I'm not convinced the issues are the same.
The only way I have found to restore things to normality is to restart, after which the PC performs correctly and the network share is restored and persists until the next incident. I have not found any possible trigger for this issue; it sometimes happens overnight when the PC is not in use and the latest incident was after the PC had not been used for a couple of hours but had performed well up to that point. There is no occasion I have found where this occurs during a period of use.
I'm reluctant to change the
managed=false flag unnecessarily since there is no firm evidence yet that this is the issue. It does not occur on 18.04 LTS with the same setting and I am not confident this is the issue causing this phenomenon.
If the issue was more widespread, I would have expected it to have been flagged by now like the WiFi dropping issue so, is this just something unanswered in isolation on this PC, has the issue already been addressed elsewhere which I have missed or could the GNOME extension adding the share to the desktop be involved some way?
I'd be grateful for any pointers as to what possibly could be causing this unusual issue.
Yes, using CAT6 cable.
sudo lshw -C network
*-network description: Ethernet interface product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:05:00.0 logical name: enp5s0 version: 15 serial: 00:e0:4a:68:33:44 size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=5.8.0-38-generic duplex=full firmware=rtl8168h-2_0.0.2 02/26/15 ip=192.168.1.169 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s resources: irq:19 ioport:d000(size=256) memory:fbc04000-fbc04fff memory:fbc00000-fbc03fff