OFH timing errors at 40 MHz on Benetel RAN650 with srsRAN gNB

[alektoja]

Environment

Hardware

• O-RU: Benetel RAN650
• DU/CU host: Ubuntu 22.04.5 LTS
• NIC for OFH: Intel Ethernet Controller E810-C for SFP
• UE: Crosscall Core-Z5, OnePlus 11 5G
• Swtich beetwen gNB and RU

Software
-Rootfs: RAN650-1v1.4.2-NM-c48047d
-srsRAN - the newest commit

• Core: Open5GS 2.7.6

Configs:
RU_40_2x2.txt
DU_40_2x2.txt

Baseline that works
At 20 MHz the Crosscall Core-Z5 registers every time and PDU session is established. Logs are clean, no OFH timing warnings.

Problem after increasing bandwidth
When switching to 40 MHz the UE fails to register or registration becomes unstable. I see repeated OFH timing messages in the gNB log, for example:
2025-08-24T14:32:00.750050 [OFH ] [I] Sector#0: received Open Fronthaul message size is '334' bytes and it is smaller than the expected IQ samples size of '336'
2025-08-24T14:32:00.750050 [OFH ] [I] Sector#0: dropped received Open Fronthaul message as no section was decoded correctly for slot '210.19' and symbol '11'
2025-08-24T14:32:00.750409 [OFH ] [W] Sector#0: missed incoming User-Plane PRACH messages for slot '722.19'
2025-08-24T14:32:02.462373 [OFH ] [I] Real-time timing worker woke up late, skipped '4' symbols
2025-08-24T14:32:02.462496 [OFH ] [I] Real-time timing worker woke up late, skipped '3' symbols
2025-08-24T14:32:02.462621 [OFH ] [I] Real-time timing worker woke up late, skipped '4' symbols
2025-08-24T14:32:04.478369 [OFH ] [I] Real-time timing worker woke up late, skipped '4' symbols

amf log:
08/24 15:21:27.470: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_TIMER (../src/amf/amf-sm.c:84)
08/24 15:21:27.470: [sbi] DEBUG: ogs_sbi_nf_state_registered(): OGS_EVENT_NAME_SBI_TIMER (../lib/sbi/nf-sm.c:285)
08/24 15:21:27.470: [sbi] DEBUG: [PATCH] http://127.0.0.200:7777/nnrf-nfm/v1/nf-instances/75048b92-80e1-41f0-a448-15019ac5819a (../lib/sbi/client.c:787)
08/24 15:21:27.470: [sbi] DEBUG: SENDING...[100] (../lib/sbi/client.c:544)
08/24 15:21:27.470: [sbi] DEBUG: [{"op":"replace","path":"/nfStatus","value":"REGISTERED"},{"op":"replace","path":"/load","value":0}] (../lib/sbi/client.c:546)
08/24 15:21:27.470: [sbi] DEBUG: [204:PATCH] http://127.0.0.200:7777/nnrf-nfm/v1/nf-instances/75048b92-80e1-41f0-a448-15019ac5819a (../lib/sbi/client.c:734)
08/24 15:21:27.470: [sbi] DEBUG: RECEIVED[0] (../lib/sbi/client.c:745)
08/24 15:21:27.470: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_CLIENT (../src/amf/amf-sm.c:84)
08/24 15:21:27.470: [sbi] DEBUG: ogs_sbi_nf_state_registered(): OGS_EVENT_NAME_SBI_CLIENT (../lib/sbi/nf-sm.c:285)
08/24 15:21:37.478: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_TIMER (../src/amf/amf-sm.c:84)
08/24 15:21:37.478: [sbi] DEBUG: ogs_sbi_nf_state_registered(): OGS_EVENT_NAME_SBI_TIMER (../lib/sbi/nf-sm.c:285)
08/24 15:21:37.478: [sbi] DEBUG: [PATCH] http://127.0.0.200:7777/nnrf-nfm/v1/nf-instances/75048b92-80e1-41f0-a448-15019ac5819a (../lib/sbi/client.c:787)
08/24 15:21:37.478: [sbi] DEBUG: SENDING...[100] (../lib/sbi/client.c:544)
08/24 15:21:37.478: [sbi] DEBUG: [{"op":"replace","path":"/nfStatus","value":"REGISTERED"},{"op":"replace","path":"/load","value":0}] (../lib/sbi/client.c:546)
08/24 15:21:37.478: [sbi] DEBUG: [204:PATCH] http://127.0.0.200:7777/nnrf-nfm/v1/nf-instances/75048b92-80e1-41f0-a448-15019ac5819a (../lib/sbi/client.c:734)
08/24 15:21:37.478: [sbi] DEBUG: RECEIVED[0] (../lib/sbi/client.c:745)
08/24 15:21:37.478: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_CLIENT (../src/amf/amf-sm.c:84)
08/24 15:21:37.478: [sbi] DEBUG: ogs_sbi_nf_state_registered(): OGS_EVENT_NAME_SBI_CLIENT (../lib/sbi/nf-sm.c:285)

The same behavior appears at 50 MHz. It affects both Crosscall Core-Z5 and OnePlus 11 5G.

Has anyone encountered this behavior? Do you see any configuration issues, or is it rather a fault of the phones?