Unstable LAN network

Question

I have Dell vostro 3558 laptop with ubuntu 18.10. I do not face any issues when I am using Wifi. However when I am using Ethernet LAN for internet, it keeps disconnecting after 10-15 minutes and again reconnects automatically after 2-3 minutes. I did not face this problem earlier when I would use windows 10.
What could be the issue and how can it be fixed?
How do I check if the hardware is alright?

       description: Wireless interface
       product: Wireless 3160
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:06:00.0
       logical name: wlp6s0
       version: 83
       serial: 18:3d:a2:f8:70:28
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.18.0-17-generic firmware=17.948900127.0 latency=0 link=no multicast=yes wireless=IEEE 802.11
       resources: irq:52 memory:f7100000-f7101fff
  *-network
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:07:00.0
       logical name: enp7s0
       version: 0c
       serial: 84:7b:eb:01:9f:c5
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8168 driverversion=8.046.00-NAPI duplex=full ip=10.10.0.195 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
       resources: irq:43 ioport:e000(size=256) memory:f7000000-f7000fff memory:f0000000-f0003fff

And

/var/log/syslog:Apr 11 08:21:15 ****-Vostro-3558 kernel: [    1.672716] r8168 0000:07:00.0 enp7s0: renamed from eth0 /var/log/syslog.1:Apr 10 21:04:41 ****-Vostro-3558 kernel: [    1.653284] r8168 0000:07:00.0 enp7s0: renamed from eth0 

oem-touchpad-alps-synaptics, 0.1: added
r8168, 8.046.00, 4.18.0-17-generic, x86_64: installed

grep -i enp7s0 /var/log/syslog* output: https://paste.ubuntu.com/p/wDbQ888K36/

I have LAN port in my dorm which is provided by the university.

option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;

send host-name = gethostname();
request subnet-mask, broadcast-address, time-offset, routers,
    domain-name, domain-name-servers, domain-search, host-name,
    dhcp6.name-servers, dhcp6.domain-search, dhcp6.fqdn, dhcp6.sntp-servers,
    netbios-name-servers, netbios-scope, interface-mtu,
    rfc3442-classless-static-routes, ntp-servers;

timeout 300;