Hey Mike, I took a look and I did find a link that needed some attention. I have removed it from the path while the transport team works on it. Let me know if you are still seeing an issue. Josh From: mikecika--- via NANOG <nanog@lists.nanog.org> Sent: Monday, August 24, 2026 9:16 PM To: nanog@lists.nanog.org Cc: mikecika@gmail.com Subject: AS7018 upstream loss via 32.130.88.22 (SF Bay Area) — per-flow, unidirectional Seeing sustained upstream packet loss on AT&T Fiber (AS7018) in the SF Bay Area that looks path-dependent rather than congestion or CPE related. Posting in case anyone at AT&T can take a look, or has seen the same. Symptoms: Upstream Seeing sustained upstream packet loss on AT&T Fiber (AS7018) in the SF Bay Area that looks path-dependent rather than congestion or CPE related. Posting in case anyone at AT&T can take a look, or has seen the same. Symptoms: Upstream collapses to ~2–5 Mbps on a 1 Gbps symmetric circuit Downstream unaffected — 219 measured transfers, 0 failures Host TCP counters show 5–14% retransmission on affected flows Per-flow: back-to-back transfers to the same destination, differing only in source port, alternate between full rate and collapsed. Once a flow establishes it stays in whichever state it started in. Affected destinations traverse 32.130.88.22 → 32.130.20.157. Destinations routing otherwise are unaffected (12 tested, 0 failures). Ruled out: CPE (3 gateways, 2 models), plan tier (5G → 1G), optics (no DDM alarms, PON O5), MTU (0% ICMP loss at all sizes), Wi-Fi (wired throughout). ~650 measurements over 7 days. Traceroutes and per-destination breakdown available on request. Anyone else seeing this on AS7018 in the Bay Area? _______________________________________________ NANOG mailing list https://urldefense.com/v3/__https://lists.nanog.org/archives/list/nanog@lists.nanog.org/message/ESBPA7A4QTSLZZ6VQFYEPN25MQLKSV5L/__;!!BhdT!h0Luc1sfVVXxXajbYsfK7V_nfeJH3KWsbXxv9nQmp_A_zAxFalMdn2ukuMgDoHNw0sN6oYdpBuKFHjEp$<https://urldefense.com/v3/__https:/lists.nanog.org/archives/list/nanog@lists.nanog.org/message/ESBPA7A4QTSLZZ6VQFYEPN25MQLKSV5L/__;!!BhdT!h0Luc1sfVVXxXajbYsfK7V_nfeJH3KWsbXxv9nQmp_A_zAxFalMdn2ukuMgDoHNw0sN6oYdpBuKFHjEp$>