bought on epic games, played for a while in june, starting again the game after 3-4 weeks prompted an update that got stuck.
reinstalled ubisoft connect. twice. same issue.
removed /uplay_download. same issue.
reinstalled the whole game again. same issue. the update gets stuck at the last 0.01GB as before.

extract from launcher_log.txt

[16652]  2021-08-05 00:00:59      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2) timed out.
[16652]  2021-08-05 00:01:05      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f) timed out.
[16652]  2021-08-05 00:01:28      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=763e823a0bbad1db27c4263d13cad782efbce8ea01bdf4fe961bf7d5d4664d01: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=763e823a0bbad1db27c4263d13cad782efbce8ea01bdf4fe961bf7d5d4664d01) timed out.
[16652]  2021-08-05 00:01:28      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f) timed out.
[16652]  2021-08-05 00:01:30      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2) timed out.
[16652]  2021-08-05 00:01:44      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f) timed out.
[16652]  2021-08-05 00:02:00      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/3/437E9C051E1B0FD9C28871E7786D569972C75009?_tkn_=exp=1628114301~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2f3%2f437E9C051E1B0FD9C28871E7786D569972C75009~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=4f08b3a3e461c2d2de3442518255ae992f2ff6acfcf589bef6862b9ebf350f9f) timed out.
[16652] 2021-08-05 00:02:00   [ 856]   ERROR   DownloadSlice.cpp (495)             Failed to download data 6 times. Aborting.
[16652] 2021-08-05 00:02:00   [ 856]   ERROR   DownloadEdisonRequired.cpp (422)         Failed to download slice 437E9C051E1B0FD9C28871E7786D569972C75009 (download: 437E9C051E1B0FD9C28871E7786D569972C75009 build: 8D073C186E6FE65FEFE1CEA074F49C9F582A4F79) to file C:/Program Files/Epic Games/AssassinsCreedValhalla/uplay_download/13504/ACValhalla_Plus.exe. Possible cdn error.
[16652]  2021-08-05 00:02:02      [  856]      ERROR      InetHttpConnection.cpp (940)                     Read from http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2: (http://uplaypc-s-ubisoft.cdn.ubi.com/uplaypc/downloads/3523/slices_v3/d/CD630105675B5EA513B0DCE16E75468E8BB880FD?_tkn_=exp=1628114302~acl=%2fuplaypc%2fdownloads%2f3523%2fslices_v3%2fd%2fCD630105675B5EA513B0DCE16E75468E8BB880FD~data=a849088b-cbbe-4b95-ba80-396789fa3b47~hmac=d17c8b874c1afe792fc42b8fb8d2764bcee8cabadce12cbba481f7617bf739b2) timed out.
[16652] 2021-08-05 00:02:02   [ 856]   ERROR   DownloadSlice.cpp (495)             Failed to download data 6 times. Aborting.
[16652] 2021-08-05 00:02:02   [ 856]   ERROR   DownloadEdisonRequired.cpp (422)         Failed to download slice CD630105675B5EA513B0DCE16E75468E8BB880FD (download: CD630105675B5EA513B0DCE16E75468E8BB880FD build: 8D073C186E6FE65FEFE1CEA074F49C9F582A4F79) to file C:/Program Files/Epic Games/AssassinsCreedValhalla/uplay_download/13504/ACValhalla_Plus.exe. Possible cdn error.

download speed was 10MB/s for most of the time. 600 GB free on disk (same disk for OS/game) so the message below is crap.