Am suffering from the same bug on a Thinkpad T470s with an Intel 8265 wifi chip running Ubuntu 17.10, Linux kernel 4.13.0-37-generic, and iwlwifi 31.560484.0. There are multiple reports like the errors below in kern.log. After a while, the machine completely locks up. Interestingly, the system only seems to lock up when transferring files using Syncthing or Resilio Sync.

Mar 31 15:36:50 albatross kernel: [66351.160529] iwlwifi 0000:3a:00.0: Microcode SW error detected.  Restarting 0x82000000.
Mar 31 15:36:50 albatross kernel: [66351.160659] iwlwifi 0000:3a:00.0: Start IWL Error Log Dump:
Mar 31 15:36:50 albatross kernel: [66351.160661] iwlwifi 0000:3a:00.0: Status: 0x00000200, count: 6
Mar 31 15:36:50 albatross kernel: [66351.160662] iwlwifi 0000:3a:00.0: Loaded firmware version: 31.560484.0
Mar 31 15:36:50 albatross kernel: [66351.160664] iwlwifi 0000:3a:00.0: 0x00000038 | BAD_COMMAND                 
Mar 31 15:36:50 albatross kernel: [66351.160665] iwlwifi 0000:3a:00.0: 0x00000220 | trm_hw_status0
Mar 31 15:36:50 albatross kernel: [66351.160667] iwlwifi 0000:3a:00.0: 0x00000000 | trm_hw_status1
Mar 31 15:36:50 albatross kernel: [66351.160668] iwlwifi 0000:3a:00.0: 0x0002495C | branchlink2
Mar 31 15:36:50 albatross kernel: [66351.160670] iwlwifi 0000:3a:00.0: 0x0003962E | interruptlink1
Mar 31 15:36:50 albatross kernel: [66351.160671] iwlwifi 0000:3a:00.0: 0x00000000 | interruptlink2
Mar 31 15:36:50 albatross kernel: [66351.160673] iwlwifi 0000:3a:00.0: 0x0065001C | data1
Mar 31 15:36:50 albatross kernel: [66351.160674] iwlwifi 0000:3a:00.0: 0x00000066 | data2
Mar 31 15:36:50 albatross kernel: [66351.160675] iwlwifi 0000:3a:00.0: 0x00000067 | data3
Mar 31 15:36:50 albatross kernel: [66351.160677] iwlwifi 0000:3a:00.0: 0x00016976 | beacon time
Mar 31 15:36:50 albatross kernel: [66351.160678] iwlwifi 0000:3a:00.0: 0x0398C5D9 | tsf low
Mar 31 15:36:50 albatross kernel: [66351.160680] iwlwifi 0000:3a:00.0: 0x00000014 | tsf hi
Mar 31 15:36:50 albatross kernel: [66351.160681] iwlwifi 0000:3a:00.0: 0x00000000 | time gp1
Mar 31 15:36:50 albatross kernel: [66351.160682] iwlwifi 0000:3a:00.0: 0x000C98DD | time gp2
Mar 31 15:36:50 albatross kernel: [66351.160684] iwlwifi 0000:3a:00.0: 0x00000001 | uCode revision type
Mar 31 15:36:50 albatross kernel: [66351.160685] iwlwifi 0000:3a:00.0: 0x0000001F | uCode version major
Mar 31 15:36:50 albatross kernel: [66351.160687] iwlwifi 0000:3a:00.0: 0x00088D64 | uCode version minor
Mar 31 15:36:50 albatross kernel: [66351.160688] iwlwifi 0000:3a:00.0: 0x00000230 | hw version
Mar 31 15:36:50 albatross kernel: [66351.160689] iwlwifi 0000:3a:00.0: 0x00C89000 | board version
Mar 31 15:36:50 albatross kernel: [66351.160691] iwlwifi 0000:3a:00.0: 0x0065001C | hcmd
Mar 31 15:36:50 albatross kernel: [66351.160692] iwlwifi 0000:3a:00.0: 0x24022082 | isr0
Mar 31 15:36:50 albatross kernel: [66351.160694] iwlwifi 0000:3a:00.0: 0x00000000 | isr1
Mar 31 15:36:50 albatross kernel: [66351.160695] iwlwifi 0000:3a:00.0: 0x28201802 | isr2
Mar 31 15:36:50 albatross kernel: [66351.160697] iwlwifi 0000:3a:00.0: 0x004120C0 | isr3
Mar 31 15:36:50 albatross kernel: [66351.160698] iwlwifi 0000:3a:00.0: 0x00000000 | isr4
Mar 31 15:36:50 albatross kernel: [66351.160699] iwlwifi 0000:3a:00.0: 0x0A8A001C | last cmd Id
Mar 31 15:36:50 albatross kernel: [66351.160701] iwlwifi 0000:3a:00.0: 0x00000000 | wait_event
Mar 31 15:36:50 albatross kernel: [66351.160702] iwlwifi 0000:3a:00.0: 0x00000094 | l2p_control
Mar 31 15:36:50 albatross kernel: [66351.160704] iwlwifi 0000:3a:00.0: 0x00018030 | l2p_duration
Mar 31 15:36:50 albatross kernel: [66351.160705] iwlwifi 0000:3a:00.0: 0x0000000F | l2p_mhvalid
Mar 31 15:36:50 albatross kernel: [66351.160706] iwlwifi 0000:3a:00.0: 0x00000085 | l2p_addr_match
Mar 31 15:36:50 albatross kernel: [66351.160708] iwlwifi 0000:3a:00.0: 0x0000000D | lmpm_pmg_sel
Mar 31 15:36:50 albatross kernel: [66351.160709] iwlwifi 0000:3a:00.0: 0x13091828 | timestamp
Mar 31 15:36:50 albatross kernel: [66351.160711] iwlwifi 0000:3a:00.0: 0x00008098 | flow_handler
Mar 31 15:36:50 albatross kernel: [66351.160777] iwlwifi 0000:3a:00.0: Start IWL Error Log Dump:
Mar 31 15:36:50 albatross kernel: [66351.160779] iwlwifi 0000:3a:00.0: Status: 0x00000200, count: 7
Mar 31 15:36:50 albatross kernel: [66351.160781] iwlwifi 0000:3a:00.0: 0x00000070 | ADVANCED_SYSASSERT
Mar 31 15:36:50 albatross kernel: [66351.160782] iwlwifi 0000:3a:00.0: 0x00000000 | umac branchlink1
Mar 31 15:36:50 albatross kernel: [66351.160783] iwlwifi 0000:3a:00.0: 0xC0086950 | umac branchlink2
Mar 31 15:36:50 albatross kernel: [66351.160785] iwlwifi 0000:3a:00.0: 0xC00842BC | umac interruptlink1
Mar 31 15:36:50 albatross kernel: [66351.160786] iwlwifi 0000:3a:00.0: 0xC00842BC | umac interruptlink2
Mar 31 15:36:50 albatross kernel: [66351.160788] iwlwifi 0000:3a:00.0: 0x00000800 | umac data1
Mar 31 15:36:50 albatross kernel: [66351.160789] iwlwifi 0000:3a:00.0: 0xC00842BC | umac data2
Mar 31 15:36:50 albatross kernel: [66351.160790] iwlwifi 0000:3a:00.0: 0xDEADBEEF | umac data3
Mar 31 15:36:50 albatross kernel: [66351.160792] iwlwifi 0000:3a:00.0: 0x0000001F | umac major
Mar 31 15:36:50 albatross kernel: [66351.160793] iwlwifi 0000:3a:00.0: 0x00088D64 | umac minor
Mar 31 15:36:50 albatross kernel: [66351.160795] iwlwifi 0000:3a:00.0: 0xC088627C | frame pointer
Mar 31 15:36:50 albatross kernel: [66351.160796] iwlwifi 0000:3a:00.0: 0xC088627C | stack pointer
Mar 31 15:36:50 albatross kernel: [66351.160797] iwlwifi 0000:3a:00.0: 0x0065001C | last host cmd
Mar 31 15:36:50 albatross kernel: [66351.160798] iwlwifi 0000:3a:00.0: 0x00000000 | isr status reg
Mar 31 15:36:50 albatross kernel: [66351.160801] ieee80211 phy0: Hardware restart was requested
Mar 31 15:36:50 albatross kernel: [66351.160808] iwlwifi 0000:3a:00.0: FW Error notification: type 0x00000000 cmd_id 0x1C
Mar 31 15:36:50 albatross kernel: [66351.160810] iwlwifi 0000:3a:00.0: FW Error notification: seq 0x0065 service 0x0000001C
Mar 31 15:36:50 albatross kernel: [66351.160811] iwlwifi 0000:3a:00.0: FW Error notification: timestamp 0x           C98DA