Diagnosing Ubuntu Ethernet Connection

I’m running Ubuntu 18.04.4 LTS, with Cinnamon as desktop environment.

Yesterday my Ethernet connection disconnected and now I can no longer use the Internet; on Chromium the error is DNS_PROBE_FINISHED_NO_INTERNET. However, in my Network Manager, I am still connected to "Wired Connection 1".

What steps do I take to diagnose where the problem is? Do I need to provide more information? I’m not familiar with networking. I’m currently using a mobile modem as a replacement.

Thanks!

Output of various commands that may be useful:

ifconfig – enp10s0 is the ethernet which is having issues.

enp10s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.7  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fd80::d95c:db70:d668:7afc  prefixlen 64  scopeid 0x0<global>
        inet6 fd80::2de8:4bea:acf9:bc9a  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::2618:40ca:20d3:6055  prefixlen 64  scopeid 0x20<link>
        ether 70:85:c2:55:07:64  txqueuelen 1000  (Ethernet)
        RX packets 2134  bytes 163311 (163.3 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1895  bytes 168216 (168.2 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 2864  bytes 234021 (234.0 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2864  bytes 234021 (234.0 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    20100  0        0 enp10s0
link-local      0.0.0.0         255.255.0.0     U     1000   0        0 enp10s0
192.168.1.0     0.0.0.0         255.255.255.0   U     100    0        0 enp10s0

ping -c4 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Destination Net Unreachable
From 192.168.1.1 icmp_seq=2 Destination Net Unreachable
From 192.168.1.1 icmp_seq=3 Destination Net Unreachable
From 192.168.1.1 icmp_seq=4 Destination Net Unreachable

--- 8.8.8.8 ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 3035ms

sudo ethtool enp10s0

Settings for enp10s0:
    Supported ports: [ TP MII ]
    Supported link modes:   10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Half 1000baseT/Full 
    Supported pause frame use: No
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Full 
    Advertised pause frame use: Symmetric Receive-only
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                         100baseT/Half 100baseT/Full 
                                         1000baseT/Full 
    Link partner advertised pause frame use: Symmetric
    Link partner advertised auto-negotiation: Yes
    Link partner advertised FEC modes: Not reported
    Speed: 1000Mb/s
    Duplex: Full
    Port: MII
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: pumbg
    Wake-on: g
    Current message level: 0x00000033 (51)
                   drv probe ifdown ifup
    Link detected: yes

ip route

default via 192.168.1.1 dev enp10s0 proto dhcp metric 20100 
169.254.0.0/16 dev enp10s0 scope link metric 1000 
192.168.1.0/24 dev enp10s0 proto kernel scope link src 192.168.1.7 metric 100