Persistent Input Latency / UCMD Delay in Apex Legends.

I've invested thousands of hours into this game and I have never experienced a more painful and torturous experience. I genuinely have reanalyzed whether I even want to continue to invest time into video games. I came back to Apex Legends to hit pred but the experience thus far has been terrible. I mean every game I lag. Literally every game this season has been plagued by constant UCMD, lag compensation error, packet loss, starvation and just pure agony. I'm honestly not even sure why I'm lagging. I'm sure the assumption would be, "oh well maybe you haven't troubleshot it enough". Nothing could be further from the truth. A prolonged troubleshooting effort was undertaken to diagnose persistent input latency and UCMD delay occurring specifically in Apex Legends. At the system level, the PC was restarted repeatedly during testing, CPU temperatures were monitored under load and observed to peak around 70°C without sustained thermal throttling, and CPU boost behavior was confirmed to reach approximately 4.2 GHz.(It was later fixed to run at 4900MHz and peaks at 83°C) The processor was verified to be an i7-9700K, which does not support Hyper-Threading by design, and BIOS settings were reset multiple times while testing various CPU power and scheduling configurations, including Intel Turbo Boost and Speed Shift behavior, without engaging in manual overclocking. Memory stability and RAM operating speeds were verified, background processes were reviewed for abnormal load, and primary NVMe storage was checked to ensure roughly 37 percent free capacity, with approximately 185 GB of data moved or deleted to rule out storage pressure. On the software and driver side, chipset drivers were checked after suspicion of being outdated and confirmed to already be current, network adapter driver and interface versions were manually verified, and redundant update loops were avoided based on prior experience. Windows PowerShell networking commands were executed to enumerate advanced network adapter properties, and multiple NIC configuration changes were tested, including interrupt moderation behavior and related driver-level settings, followed by system reboots to confirm persistence. Windows power plans were adjusted to high-performance modes, network power-saving features were disabled, and a full Windows reinstall or network stack reset was considered but not executed at that stage. From a networking standpoint, IPv6 was disabled, both wired and wireless configurations were tested with Ethernet favored, and the physical Ethernet path was confirmed to be direct with no inline adapters. Network stability was repeatedly validated by pinging the local gateway as well as external endpoints such as public DNS servers, consistently showing stable latency and zero packet loss. Local router latency was measured at approximately 0–2 ms, and network behavior was observed to remain stable even during simultaneous household usage, indicating no correlation with bandwidth saturation or packet loss. Potential DOCSIS-level issues, including node congestion, OFDMA instability, and Puma chipset defects, were investigated, with confirmation that the XB7-CM modem does not use a Puma chipset. Alternative networking solutions such as MoCA adapters, point-to-point wireless bridges, CAT6 versus CAT6A cabling, fiber availability, and modem or router replacement were researched, and additional household network devices such as NAS units and TV equipment were disconnected or inspected to rule out background traffic. Large fluctuations in reported aggregated link speed were observed and compared against gameplay behavior, with no consistent relationship identified. This later changed with the purchase of a CAT 6 cable, which now offers stable network. Within Apex Legends, the issue was characterized as persistent input latency rather than traditional network lag, occurring despite stable ping, absence of packet loss(at times), consistent frame rates(generally), and no in-game network warning icons. The delay presented as command processing or desynchronization rather than rubber-banding, varied between matches within the same session, and appeared disproportionately severe in Apex compared to other games. Multiple sessions and modes were tested, teammate behavior and server population were ruled out as primary factors, and potential causes such as ISP routing, engine-level netcode sensitivity, system scheduling behavior, and network buffering were evaluated. Throughout the process, variables were intentionally isolated where possible, circular troubleshooting paths were avoided, diagnostic fatigue was reached, and a full system reset or discontinuation of further troubleshooting was seriously considered after most non-destructive avenues had been exhausted. I'm not sure what else to do, I just want to be able to run the game smooth. Whenever I get into a gunfight, me winning is completely dependent upon whether my system decides to not sh*t itself. I need help. I've been troubleshooting now since the beginning of the season 27 ranked split and this is killing me slowly. Please support, reach out and help me.