Ubuntu 22.04 can't connect to network over any interface [FIXED]

Question

I recently upgraded a Ubuntu 20.04 LTS system to Ubuntu 22.04 LTS, and things seemed to be going well enough with a few small issues.

However, this morning, my network connection dropped and refused to reconnect.

1. I tried the other network interface on the motherboard: No dice.

2. I tried a USB ethernet interface: No dice.

3. I tried a USB WiFi interface: No dice.

It appears that (regardless of the network interface), Ubuntu churns for a while and then gives up. There is a NETDEV WATCHDOG message in dmesg (below), but none of the other interfaces I try have that issue. They all report a link connection, then they timeout, drop the connection, and reset the interface. Everything else on my home network is working fine.

[   74.355975] ------------[ cut here ]------------
[   74.356000] NETDEV WATCHDOG: enp5s0 (igb): transmit queue 0 timed out
[   74.356047] WARNING: CPU: 13 PID: 0 at net/sched/sch_generic.c:477 dev_watchdog+0x277/0x280
[   74.356069] Modules linked in: vboxnetadp(OE) vboxnetflt(OE) vboxdrv(OE) snd_seq_dummy rfcomm snd_hrtimer nvidia_uvm(POE) cmac algif_hash xt_state algif_skcipher xt_conntrack af_alg nft_counter bnep intel_rapl_msr intel_rapl_common sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd nft_chain_nat nvidia_drm(POE) nvidia_modeset(POE) rapl kvm_intel xt_MASQUERADE nf_nat nvidia(POE) nf_conntrack kvm nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables libcrc32c binfmt_misc nfnetlink snd_hda_codec_realtek btusb hp_wmi snd_hda_codec_generic sparse_keymap btrtl snd_hda_codec_hdmi platform_profile ledtrig_audio btbcm intel_cstate serio_raw wmi_bmof btintel snd_usb_audio bluetooth nls_iso8859_1 snd_hda_intel snd_usbmidi_lib pl2303 ecdh_generic snd_intel_dspcfg snd_seq_midi snd_intel_sdw_acpi ecc usbserial uvcvideo snd_seq_midi_event snd_hda_codec snd_rawmidi videobuf2_vmalloc snd_hda_core videobuf2_memops snd_hwdep
[   74.356453]  videobuf2_v4l2 joydev input_leds videobuf2_common snd_pcm drm_kms_helper snd_seq mei_me mei cec snd_seq_device snd_timer rc_core fb_sys_fops syscopyarea snd sysfillrect sysimgblt soundcore tpm_infineon mac_hid sch_fq_codel ipmi_devintf ipmi_msghandler msr videodev mc parport_pc ppdev lp ramoops parport nfsd reed_solomon pstore_blk pstore_zone mtd auth_rpcgss nfs_acl drm lockd efi_pstore grace sunrpc ip_tables x_tables autofs4 uas hid_generic usb_storage usbhid hid igb crc32_pclmul psmouse mpt3sas nvme i2c_i801 i2c_algo_bit xhci_pci raid_class ahci e1000e i2c_smbus lpc_ich dca nvme_core xhci_pci_renesas libahci scsi_transport_sas wmi
[   74.356785] CPU: 13 PID: 0 Comm: swapper/13 Tainted: P           OE     5.15.0-46-generic #49-Ubuntu
[   74.356794] Hardware name: Hewlett-Packard HP Z840 Workstation/2129, BIOS M60 v02.56 11/04/2020
[   74.356799] RIP: 0010:dev_watchdog+0x277/0x280
[   74.356811] Code: eb 97 48 8b 5d d0 c6 05 de 5e 69 01 01 48 89 df e8 de 67 f9 ff 44 89 e1 48 89 de 48 c7 c7 f0 2b 0d a2 48 89 c2 e8 d3 c1 19 00 <0f> 0b eb 80 e9 0b 26 23 00 0f 1f 44 00 00 55 48 89 e5 41 57 41 56
[   74.356818] RSP: 0018:ffffa13486710e70 EFLAGS: 00010282
[   74.356830] RAX: 0000000000000000 RBX: ffff89e214114000 RCX: 000000000000083f
[   74.356836] RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
[   74.356843] RBP: ffffa13486710ea8 R08: 0000000000000003 R09: fffffffffffde4e0
[   74.356849] R10: 0000000000ffff0a R11: 0000000000000001 R12: 0000000000000000
[   74.356854] R13: ffff89e205304940 R14: 0000000000000008 R15: ffff89e2141144c0
[   74.356859] FS:  0000000000000000(0000) GS:ffff89e90fbc0000(0000) knlGS:0000000000000000
[   74.356866] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   74.356872] CR2: 00007fd868002538 CR3: 0000000b6ce10003 CR4: 00000000001706e0
[   74.356878] Call Trace:
[   74.356884]  <IRQ>
[   74.356893]  ? pfifo_fast_enqueue+0x160/0x160
[   74.356906]  call_timer_fn+0x2b/0x120
[   74.356918]  __run_timers.part.0+0x1e3/0x270
[   74.356925]  ? ktime_get+0x46/0xc0
[   74.356935]  ? lapic_next_deadline+0x2c/0x40
[   74.356949]  ? clockevents_program_event+0xad/0x130
[   74.356962]  run_timer_softirq+0x2a/0x60
[   74.356968]  __do_softirq+0xd9/0x2e7
[   74.356982]  irq_exit_rcu+0x94/0xc0
[   74.356996]  sysvec_apic_timer_interrupt+0x80/0x90
[   74.357009]  </IRQ>
[   74.357012]  <TASK>
[   74.357015]  asm_sysvec_apic_timer_interrupt+0x1a/0x20
[   74.357022] RIP: 0010:cpuidle_enter_state+0xd9/0x620
[   74.357038] Code: 3d f4 04 ba 5e e8 17 e7 68 ff 49 89 c7 0f 1f 44 00 00 31 ff e8 58 f4 68 ff 80 7d d0 00 0f 85 61 01 00 00 fb 66 0f 1f 44 00 00 <45> 85 f6 0f 88 6d 01 00 00 4d 63 ee 49 83 fd 09 0f 87 e7 03 00 00
[   74.357043] RSP: 0018:ffffa1348640fe28 EFLAGS: 00000246
[   74.357050] RAX: ffff89e90fbf0b00 RBX: ffffc12c7fbc2100 RCX: 0000000000000000
[   74.357054] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
[   74.357058] RBP: ffffa1348640fe78 R08: 000000114ff5f078 R09: 0000000000000000
[   74.357062] R10: 0000000000000001 R11: 071c71c71c71c71c R12: ffffffffa2ad3a00
[   74.357067] R13: 0000000000000004 R14: 0000000000000004 R15: 000000114ff5f078
[   74.357076]  ? cpuidle_enter_state+0xc8/0x620
[   74.357085]  ? tick_nohz_stop_tick+0x16a/0x1d0
[   74.357091]  cpuidle_enter+0x2e/0x50
[   74.357099]  cpuidle_idle_call+0x142/0x1e0
[   74.357111]  do_idle+0x83/0xf0
[   74.357118]  cpu_startup_entry+0x20/0x30
[   74.357126]  start_secondary+0x12a/0x180
[   74.357134]  secondary_startup_64_no_verify+0xc2/0xcb
[   74.357147]  </TASK>
[   74.357152] ---[ end trace f49bbe0ef2a40b70 ]---

Update 1: I've also tried booting directly from a 22.04LTS USB Live. Same issue. I then tried booting from a 20.04LTS USB Live. Also same issue across any interface I tried: Motherboard, USB Adapter, USB WiFi. All try to connect and fail. Again, everything else on the home network is fine. If it wasn't for the fact that any network interface I try fails, I'd say it was a hardware issue.

Update 2: I've tried different cables and ports, of course. At least from the log messages there doesn't seem to be an issue with the link. I've gotten a USB WiFi stick to work only by unplugging everything else. It still occasionally disassociates (don't we all?) and has to fumble around and reconnect, even with good signal strength. Maybe this is a hardware issue (various live USB sticks are leading me that way?), but the fact that a USB Wired Ethernet adapter refuses to work is super confusing.

Update 3: Shutting off DHCP "fixed" it? Now I'm super confused, but I'm wondering now if there's a problem with my router.

Update 4: WELP, a router reboot made it go away. not sure why it was singling out one machine out of all of them on the network, but that's what was happening.