Gfilui

So I'm aware that I'm not the first one who encounter the issue, and have consulted the answer in this question, not forget to mention that also similar issues occur here, here, and here. None of them solves my problem. So I'm kindly asking for a solution if possible. Here are the outputs of the network.

 $ ifconfig
 enp4s0 Link encap:Ethernet HWaddr 08:62:66:a0:32:91 
 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
 RX packets:0 errors:0 dropped:0 overruns:0 frame:0
 TX packets:289 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000 
 RX bytes:0 (0.0 B) TX bytes:51524 (51.5 KB)

 lo Link encap:Local Loopback 
 inet addr:127.0.0.1 Mask:255.0.0.0
 inet6 addr: ::1/128 Scope:Host
 UP LOOPBACK RUNNING MTU:65536 Metric:1
 RX packets:7856 errors:0 dropped:0 overruns:0 frame:0
 TX packets:7856 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1 
 RX bytes:5030852 (5.0 MB) TX bytes:5030852 (5.0 MB)

 wlp5s0 Link encap:Ethernet HWaddr 40:e2:30:b4:65:dd 
 inet addr:192.168.1.9 Bcast:192.168.1.255 Mask:255.255.255.0
 inet6 addr: fe80::2a86:c9bf:189e:9a2b/64 Scope:Link
 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
 RX packets:12096 errors:0 dropped:0 overruns:0 frame:0
 TX packets:12567 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000 
 RX bytes:5963240 (5.9 MB) TX bytes:4682030 (4.6 MB)

 $ lshw -C network 
 WARNING: you should run this program as super-user.
 *-network DISABLED 
 description: Ethernet interface
 product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
 vendor: Realtek Semiconductor Co., Ltd.
 physical id: 0
 bus info: pci@0000:04:00.0
 logical name: enp4s0
 version: 0c
 serial: 08:62:66:a0:32:91
 size: 10Mbit/s
 capacity: 1Gbit/s
 width: 64 bits
 clock: 33MHz
 capabilities: bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
 configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full latency=0 link=no multicast=yes port=MII speed=10Mbit/s
 resources: irq:33 ioport:e000(size=256) memory:fe900000-fe900fff memory:f0000000-f0003fff
 *-network
 description: Wireless interface
 product: RTL8821AE 802.11ac PCIe Wireless Network Adapter
 vendor: Realtek Semiconductor Co., Ltd.
 physical id: 0
 bus info: pci@0000:05:00.0
 logical name: wlp5s0
 version: 00
 serial: 40:e2:30:b4:65:dd
 width: 64 bits
 clock: 33MHz
 capabilities: bus_master cap_list ethernet physical wireless
 configuration: broadcast=yes driver=rtl8821ae driverversion=4.4.0-119-generic firmware=N/A ip=192.168.1.9 latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn
 resources: irq:32 ioport:d000(size=256) memory:fe800000-fe803fff
 WARNING: output may be incomplete or inaccurate, you should run this program as super-user

 $ cat /etc/network/interfaces
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
 auto enp4s0
 iface enp4s0 inet static
 # address 192.168.1.10
 # gateway 192.168.1.1
 # netmask 255.255.255.0
 # dns-nameservers 8.8.8.8

 $ lsb_release -a
 No LSB modules are available.
 Distributor ID: Ubuntu
 Description: Ubuntu 16.04.4 LTS
 Release: 16.04
 Codename: xenial

 $ lsmod | grep r816*
 r8169 86016 0
 mii 16384 1 r8169

 $ dmesg | grep "eth0" 
 [ 539.765454] r8169 0000:04:00.0 eth0: RTL8168g/8111g at 0xffffc90001c0a000, 08:62:66:a0:32:91, XID 0c000800 IRQ 33
 [ 539.765461] r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
 [ 539.781532] r8169 0000:04:00.0 enp4s0: renamed from eth0
 [ 4393.209115] r8169 0000:04:00.0 eth0: RTL8168g/8111g at 0xffffc90001c0a000, 08:62:66:a0:32:91, XID 0c000880 IRQ 33
 [ 4393.209120] r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
 [ 4393.213831] r8169 0000:04:00.0 enp4s0: renamed from eth0

I realize my problem is similar to this, so I've installed the dkms and r8168-dkms packages via WiFi (I'm lucky to have a WiFi card on the motherboard). This has resulted in the Ethernet doesn't activate once computer is rebooted (the Ethernet light in the back of CPU is completely off). I have to manually activate using

 sudo modprobe -r r8169
 sudo modprobe r8169
 sudo service network-manager restart

then the Ethernet light starts again, but it still doesn't connect to the Internet via Ethernet. Some suggest the interface name has changed, so I take a look at /etc/network/interface and update the name enp4s0. I'd like to connect to the Internet via Ethernet mode, even though I also have wireless connection and it's working. Please let me know how to solve the problem. Thank you in advance!