Hi, I have noticed a possible bug in iwlwifi related to CMD_[CANCEL_]REMAIN_ON_CHANNEL. I have connected to an AP, then in a loop: - Call CMD_REMAIN_ON_CHANNEL - Wait for NL80211 ACK - Wait for the ROC event - Send a frame - Wait for CANCEL_ROC event - Repeat Note sometimes the driver will deny the ROC request an immediately send Cancel ROC, which is fine. Specifically with about a 200ms duration I notice that eventually no ROC event comes in. NL80211 ACKs my request which has a cookie but no events follow. Not sure what exactly is going on but it appears to be related to iwlwifi specifically: < Request: Remain on Channel (0x37) len 28 [ack] 1638898585.172028 Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Duration: 200 (0x000000c8) > Result: Remain on Channel (0x37) len 12 1638898585.179108 Cookie: 7075 (0x0000000000001ba3) > Response: Remain on Channel (0x37) len 4 [0x100] 1638898585.179117 Status: Success (0) > Event: Cancel Remain on Channel (0x38) len 56 1638898585.478102 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Wiphy Channel Type: 0 (0x00000000) Cookie: 7075 (0x0000000000001ba3) < Request: Remain on Channel (0x37) len 28 [ack] 1638898585.478214 Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Duration: 200 (0x000000c8) > Result: Remain on Channel (0x37) len 12 1638898585.489078 Cookie: 7076 (0x0000000000001ba4) > Response: Remain on Channel (0x37) len 4 [0x100] 1638898585.489088 Status: Success (0) > Event: Remain on Channel (0x37) len 64 1638898585.672127 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Wiphy Channel Type: 0 (0x00000000) Cookie: 7076 (0x0000000000001ba4) Duration: 200 (0x000000c8) < Request: Frame (0x3b) len 96 [ack] 1638898585.672333 Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Offchannel TX OK: true Frame: len 68 Frame Type: 0x00d0 Type: Management (0) Subtype: Action Action Category: Public (4) Public Action: Vendor-specific (9) d0 00 00 00 ff ff ff ff ff ff 7c 7a 91 2b d8 0b ..........|z.+.. ff ff ff ff ff ff 00 00 04 09 50 6f 9a 1a 01 0d ..........Po.... 02 10 20 00 6a 1d 82 fa c1 f2 5f 48 3e 13 1b 99 .. .j....._H>... a3 92 7c 93 20 90 0a 06 34 78 fe 54 04 57 42 01 ..|. ...4x.T.WB. 7d b2 7a 89 }.z. > Result: Frame (0x3b) len 12 1638898585.672377 Cookie: 7077 (0x0000000000001ba5) > Response: Frame (0x3b) len 4 [0x100] 1638898585.672380 Status: Success (0) > Event: Frame TX Status (0x3c) len 116 1638898585.673263 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Frame: len 68 Frame Type: 0x00d0 Type: Management (0) Subtype: Action Action Category: Public (4) Public Action: Vendor-specific (9) d0 00 00 00 ff ff ff ff ff ff 7c 7a 91 2b d8 0b ..........|z.+.. ff ff ff ff ff ff 00 00 04 09 50 6f 9a 1a 01 0d ..........Po.... 02 10 20 00 6a 1d 82 fa c1 f2 5f 48 3e 13 1b 99 .. .j....._H>... a3 92 7c 93 20 90 0a 06 34 78 fe 54 04 57 42 01 ..|. ...4x.T.WB. 7d b2 7a 89 }.z. Cookie: 7077 (0x0000000000001ba5) ACK: true > Event: Cancel Remain on Channel (0x38) len 56 1638898585.867523 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Wiphy Channel Type: 0 (0x00000000) Cookie: 7076 (0x0000000000001ba4) > Event: Frame Wait Cancel (0x43) len 56 1638898585.867539 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Wiphy Channel Type: 0 (0x00000000) Cookie: 7077 (0x0000000000001ba5) < Request: Remain on Channel (0x37) len 28 [ack] 1638898585.867664 Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Duration: 200 (0x000000c8) > Result: Remain on Channel (0x37) len 12 1638898585.881073 Cookie: 7078 (0x0000000000001ba6) > Response: Remain on Channel (0x37) len 4 [0x100] 1638898585.881085 Status: Success (0) > Event: Cancel Remain on Channel (0x38) len 56 1638898585.975207 Wiphy: 0 (0x00000000) Interface Index: 3 (0x00000003) Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Wiphy Channel Type: 0 (0x00000000) Cookie: 7078 (0x0000000000001ba6) < Request: Remain on Channel (0x37) len 28 [ack] 1638898585.975359 Wireless Device: 1 (0x0000000000000001) Wiphy Frequency: 2437 (0x00000985) Duration: 200 (0x000000c8) > Result: Remain on Channel (0x37) len 12 1638898585.987983 Cookie: 7079 (0x0000000000001ba7) > Response: Remain on Channel (0x37) len 4 [0x100] 1638898585.988007 Status: Success (0) ... And nothing after this point. My code is waiting for the ROC/Cancel event but it never comes. I have tested mt76x2u, several rtl* cards, and rt2800usb and not seen this behavior. It only happens on my iwlwifi card and only while connected. Thanks, James