I've a similar bug occurring on the following kernel versions:
* 5.0.0-23-generic
* 5.0.0-25-generic
* 5.0.0-27-generic

However, quite a few things are different in my case.
As seen in logs, "Link is Down" is quickly followed up by "Link is Up" message, but interface fails to serve any packets. As far as packet statistics go, packets are transmitted, but never received.

Kernel logs also show this interesting backtrace:

12:04:55 kernel: ------------[ cut here ]------------
12:04:55 kernel: NETDEV WATCHDOG: enp3s0f1 (r8169): transmit queue 0 timed out
12:04:55 kernel: WARNING: CPU: 4 PID: 0 at /build/linux-hwe-zHO4ZF/linux-hwe-5.0.0/net/sched/sch_generic.c:461 dev_watchdog+0x221/0x230
12:04:55 kernel: Modules linked in: ccm ipt_MASQUERADE nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo iptable_nat nf_nat_ipv4 xt_addrtype iptable_filter bpfilter xt_conntrack nf_nat nf_
12:04:55 kernel:  intel_rapl_perf rtsx_pci_ms asus_nb_wmi snd joydev input_leds mei_me asus_wmi soundcore memstick serio_raw sparse_keymap mei mxm_wmi processor_thermal_device intel_pch_the
12:04:55 kernel: CPU: 4 PID: 0 Comm: swapper/4 Tainted: P           OE     5.0.0-23-generic #24~18.04.1-Ubuntu
12:04:55 kernel: Hardware name: ASUSTeK COMPUTER INC. X550VX/X550VX, BIOS X550VX.302 05/04/2017
12:04:55 kernel: RIP: 0010:dev_watchdog+0x221/0x230
12:04:55 kernel: Code: 00 49 63 4e e0 eb 92 4c 89 ef c6 05 ba 0a f0 00 01 e8 03 39 fc ff 89 d9 48 89 c2 4c 89 ee 48 c7 c7 a0 8d da a3 e8 4f 63 79 ff <0f> 0b eb c0 90 66 2e 0f 1f 84 00 00 00
12:04:55 kernel: RSP: 0018:ffff968437b03e58 EFLAGS: 00010286
12:04:55 kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006
12:04:55 kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff968437b16440
12:04:55 kernel: RBP: ffff968437b03e88 R08: 00000000000003ca R09: 0000000000000004
12:04:55 kernel: R10: ffff968437b03ee0 R11: 0000000000000001 R12: 0000000000000001
12:04:55 kernel: R13: ffff9684352b0000 R14: ffff9684352b04c0 R15: ffff968429a4da80
12:04:55 kernel: FS:  0000000000000000(0000) GS:ffff968437b00000(0000) knlGS:0000000000000000
12:04:55 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
12:04:55 kernel: CR2: 00007f8bce55be90 CR3: 0000000230a0e004 CR4: 00000000003606e0
12:04:55 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
12:04:55 kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
12:04:55 kernel: Call Trace:
12:04:55 kernel:  <IRQ>
12:04:55 kernel:  ? pfifo_fast_reset+0x110/0x110
12:04:55 kernel:  call_timer_fn+0x30/0x130
12:04:55 kernel:  run_timer_softirq+0x3ff/0x450
12:04:55 kernel: CPU: 4 PID: 0 Comm: swapper/4 Tainted: P           OE     5.0.0-23-generic #24~18.04.1-Ubuntu
12:04:55 kernel: Hardware name: ASUSTeK COMPUTER INC. X550VX/X550VX, BIOS X550VX.302 05/04/2017
12:04:55 kernel: RIP: 0010:dev_watchdog+0x221/0x230
12:04:55 kernel: Code: 00 49 63 4e e0 eb 92 4c 89 ef c6 05 ba 0a f0 00 01 e8 03 39 fc ff 89 d9 48 89 c2 4c 89 ee 48 c
12:04:55 kernel: RSP: 0018:ffff968437b03e58 EFLAGS: 00010286
12:04:55 kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006
12:04:55 kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff968437b16440
12:04:55 kernel: RBP: ffff968437b03e88 R08: 00000000000003ca R09: 0000000000000004
12:04:55 kernel: R10: ffff968437b03ee0 R11: 0000000000000001 R12: 0000000000000001
12:04:55 kernel: R13: ffff9684352b0000 R14: ffff9684352b04c0 R15: ffff968429a4da80
12:04:55 kernel: FS:  0000000000000000(0000) GS:ffff968437b00000(0000) knlGS:0000000000000000
12:04:55 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
12:04:55 kernel: CR2: 00007f8bce55be90 CR3: 0000000230a0e004 CR4: 00000000003606e0
12:04:55 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
12:04:55 kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
12:04:55 kernel: Call Trace:
12:04:55 kernel:  <IRQ>
12:04:55 kernel:  ? pfifo_fast_reset+0x110/0x110
12:04:55 kernel:  call_timer_fn+0x30/0x130
12:04:55 kernel:  run_timer_softirq+0x3ff/0x450
12:04:55 kernel: Hardware name: ASUSTeK COMPUTER INC. X550VX/X550VX, BIOS X550VX.302 05/04/2017
12:04:55 kernel: RIP: 0010:dev_watchdog+0x221/0x230
12:04:55 kernel: Code: 00 49 63 4e e0 eb 92 4c 89 ef c6 05 ba 0a f0 00 01 e8 03 39 fc ff 89 d9 48 89 c2 4c 89 ee 48 c7 c7 a0 8d da a3 e8 4f 63 79 ff <0f> 0b eb c0 90 66 2e 0f 1f 84 00 00 00
12:04:55 kernel: RSP: 0018:ffff968437b03e58 EFLAGS: 00010286
12:04:55 kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006
12:04:55 kernel: RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff968437b16440
12:04:55 kernel: RBP: ffff968437b03e88 R08: 00000000000003ca R09: 0000000000000004
12:04:55 kernel: R10: ffff968437b03ee0 R11: 0000000000000001 R12: 0000000000000001
12:04:55 kernel: R13: ffff9684352b0000 R14: ffff9684352b04c0 R15: ffff968429a4da80
12:04:55 kernel: FS:  0000000000000000(0000) GS:ffff968437b00000(0000) knlGS:0000000000000000
12:04:55 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
12:04:55 kernel: CR2: 00007f8bce55be90 CR3: 0000000230a0e004 CR4: 00000000003606e0
12:04:55 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
12:04:55 kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
12:04:55 kernel: Call Trace:
12:04:55 kernel:  <IRQ>
12:04:55 kernel:  ? pfifo_fast_reset+0x110/0x110
12:04:55 kernel:  call_timer_fn+0x30/0x130
12:04:55 kernel:  run_timer_softirq+0x3ff/0x450
12:04:55 kernel:  ? ktime_get+0x43/0xa0
12:04:55 kernel:  ? lapic_next_deadline+0x26/0x30
12:04:55 kernel:  __do_softirq+0xe4/0x2f3
12:04:55 kernel:  irq_exit+0xc5/0xd0
12:04:55 kernel:  smp_apic_timer_interrupt+0x79/0x140
12:04:55 kernel:  apic_timer_interrupt+0xf/0x20
12:04:55 kernel:  </IRQ>
12:04:55 kernel: RIP: 0010:cpuidle_enter_state+0xbc/0x440
12:04:55 kernel: Code: ff e8 88 c1 86 ff 80 7d d3 00 74 17 9c 58 0f 1f 44 00 00 f6 c4 02 0f 85 54 03 00 00 31 ff e8 4b fd 8c ff fb 66 0f 1f 44 00 00 <45> 85 ed 0f 88 1a 03 00 00 4c 2b 7d c8
12:04:55 kernel: RSP: 0018:ffffba2841967e60 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
12:04:55 kernel: RAX: ffff968437b22d80 RBX: ffffffffa4153d40 RCX: 000000000000001f
12:04:55 kernel: RDX: 0000000a83340bec RSI: 000000003161f9ae RDI: 0000000000000000
12:04:55 kernel: RBP: ffffba2841967ea0 R08: 0000000000000000 R09: 0000000000022640
12:04:55 kernel: R10: ffffba2841967e30 R11: 0000000000001efc R12: ffff968437b2d100
12:04:55 kernel: R13: 0000000000000006 R14: ffffffffa4153f98 R15: 0000000a83340bec
12:04:55 kernel:  cpuidle_enter+0x17/0x20
12:04:55 kernel:  call_cpuidle+0x23/0x40
12:04:55 kernel:  do_idle+0x204/0x280
12:04:55 kernel:  cpu_startup_entry+0x1d/0x20
12:04:55 kernel:  start_secondary+0x1ab/0x200
12:04:55 kernel:  secondary_startup_64+0xa4/0xb0
12:04:55 kernel: ---[ end trace 05c56515e652ec60 ]---


More logs with generic errors (this is specific to 5.0.0-27-generic kernel):

12:05:22 kernel: r8169 0000:03:00.1 enp3s0f1: Link is Down
12:05:24 kernel: r8169 0000:03:00.1: can't disable ASPM; OS doesn't have ASPM control
12:05:24 kernel: libphy: r8169: probed
12:05:24 kernel: r8169 0000:03:00.1 eth0: RTL8411, 60:45:cb:1f:5a:92, XID 5c8, IRQ 125
12:05:24 kernel: r8169 0000:03:00.1 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
12:05:24 kernel: r8169 0000:03:00.1 enp3s0f1: renamed from eth0
12:05:24 kernel: Generic PHY r8169-301:00: attached PHY driver [Generic PHY] (mii_bus:phy_addr=r8169-301:00, irq=IGNORE)
12:05:25 kernel: r8169 0000:03:00.1 enp3s0f1: Link is Down
12:05:26 kernel: r8169 0000:03:00.1 enp3s0f1: Link is Up - 100Mbps/Full - flow control rx/tx
12:05:26 kernel: IPv6: ADDRCONF(NETDEV_CHANGE): enp3s0f1: link becomes ready