Thanks hnyman.
Thanks for explaining the build. I am indeed using latest development master. Currently R7800-master-r16972-3dabb62581-20210620-1954-sysupgrade.bin
In system logs I see:
Mon Jun 21 11:43:39 2021 kern.warn kernel: [ 729.086471] print_req_error: 2 callbacks suppressed
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.086480] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.116521] blk_update_request: I/O error, dev mtdblock0, sector 8 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.117661] blk_update_request: I/O error, dev mtdblock0, sector 16 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.127667] blk_update_request: I/O error, dev mtdblock0, sector 24 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.176226] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.176269] Buffer I/O error on dev mtdblock0, logical block 0, async page read
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.190374] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.192673] Buffer I/O error on dev mtdblock0, logical block 0, async page read
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.204770] blk_update_request: I/O error, dev mtdblock1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.211649] blk_update_request: I/O error, dev mtdblock1, sector 8 op 0x0:(READ) flags 0x80700 phys_seg 3 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.222395] blk_update_request: I/O error, dev mtdblock1, sector 16 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.233076] blk_update_request: I/O error, dev mtdblock1, sector 24 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.243772] Buffer I/O error on dev mtdblock1, logical block 0, async page read
Mon Jun 21 11:43:39 2021 kern.err kernel: [ 729.262870] Buffer I/O error on dev mtdblock1, logical block 0, async page read
> Blockquote
[ 729.086471] print_req_error: 2 callbacks suppressed
[ 729.086480] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
[ 729.116521] blk_update_request: I/O error, dev mtdblock0, sector 8 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
[ 729.117661] blk_update_request: I/O error, dev mtdblock0, sector 16 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[ 729.127667] blk_update_request: I/O error, dev mtdblock0, sector 24 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[ 729.176226] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 729.176269] Buffer I/O error on dev mtdblock0, logical block 0, async page read
[ 729.190374] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 729.192673] Buffer I/O error on dev mtdblock0, logical block 0, async page read
[ 729.204770] blk_update_request: I/O error, dev mtdblock1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
[ 729.211649] blk_update_request: I/O error, dev mtdblock1, sector 8 op 0x0:(READ) flags 0x80700 phys_seg 3 prio class 0
[ 729.222395] blk_update_request: I/O error, dev mtdblock1, sector 16 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
[ 729.233076] blk_update_request: I/O error, dev mtdblock1, sector 24 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[ 729.243772] Buffer I/O error on dev mtdblock1, logical block 0, async page read
[ 729.262870] Buffer I/O error on dev mtdblock1, logical block 0, async page read
Sysupgrade without settings: tried multiple times, different build. No effect, also not with v19 build.
Luci reset: tried multiple times. No effect.
Will unplug all cables except one and continue debugging. The issues started after upgrade to latest master on 17th with 17th build. Before the upgrade it was stable. No other changes (software nor hardware) as far as I am aware.