Ok, I activated logging and tried to reach the webserver after 2 hours.
The logs are quite big (8MB) so I had to upload them:
https://www.xup.in/dl,20851514/log_deconz.txt/
Additionally I monitored the process with top and tried to reach the webserver again and control lights via Alexa:
top - 21:15:07 up 4:02, 2 users, load average: 1,29, 1,08, 1,03
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,5 us, 4,8 sy, 0,0 ni, 85,7 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8068,7 free, 4086,0 used, 4873,1 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11780,8 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,0 0,9 58:08.29 deCONZ
top - 21:15:10 up 4:02, 2 users, load average: 1,34, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,1 us, 4,7 sy, 0,0 ni, 85,2 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8050,8 free, 4103,9 used, 4873,2 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11762,8 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 101,0 0,9 58:11.32 deCONZ
top - 21:15:13 up 4:02, 2 users, load average: 1,40, 1,11, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,2 us, 4,5 sy, 0,0 ni, 85,0 id, 0,0 wa, 0,0 hi, 0,2 si, 0,0 st
MiB Spch: 15866,8 total, 8053,5 free, 4101,2 used, 4873,2 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11765,6 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 58:14.34 deCONZ
top - 21:15:16 up 4:02, 2 users, load average: 1,40, 1,11, 1,04
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 4,8 us, 1,0 sy, 0,0 ni, 94,0 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8052,8 free, 4101,9 used, 4873,2 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11764,8 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 7,0 0,9 58:14.55 deCONZ
top - 21:15:19 up 4:02, 2 users, load average: 1,36, 1,11, 1,04
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 5,4 us, 1,1 sy, 0,2 ni, 93,1 id, 0,0 wa, 0,0 hi, 0,3 si, 0,0 st
MiB Spch: 15866,8 total, 8052,3 free, 4102,4 used, 4873,3 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11764,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 3,0 0,9 58:14.64 deCONZ
top - 21:15:22 up 4:02, 2 users, load average: 1,36, 1,11, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 5,1 us, 1,1 sy, 0,1 ni, 93,5 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8051,4 free, 4103,3 used, 4873,3 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11763,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 7,3 0,9 58:14.86 deCONZ
top - 21:15:25 up 4:02, 2 users, load average: 1,33, 1,11, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,9 us, 4,5 sy, 0,0 ni, 85,5 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8051,3 free, 4103,4 used, 4873,3 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11763,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,3 0,9 58:17.88 deCONZ
top - 21:15:28 up 4:02, 2 users, load average: 1,31, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,1 us, 4,3 sy, 0,0 ni, 85,6 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8051,1 free, 4103,6 used, 4873,3 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11763,2 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,3 0,9 58:20.89 deCONZ
top - 21:15:31 up 4:02, 2 users, load average: 1,31, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,7 us, 4,5 sy, 0,4 ni, 84,2 id, 0,2 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8036,5 free, 4115,0 used, 4876,4 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11751,8 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 58:23.91 deCONZ
top - 21:15:34 up 4:02, 2 users, load average: 1,28, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,0 us, 4,4 sy, 0,0 ni, 85,5 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8037,3 free, 4114,0 used, 4876,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11752,7 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 99,7 0,9 58:26.90 deCONZ
top - 21:15:37 up 4:02, 2 users, load average: 1,28, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 11,7 us, 4,8 sy, 0,1 ni, 83,4 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8034,9 free, 4116,4 used, 4876,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,3 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 58:29.92 deCONZ
top - 21:15:40 up 4:02, 2 users, load average: 1,26, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,7 us, 4,0 sy, 0,0 ni, 85,1 id, 0,1 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8034,9 free, 4116,4 used, 4876,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,3 0,9 58:32.94 deCONZ
top - 21:15:43 up 4:03, 2 users, load average: 1,24, 1,10, 1,04
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 8,1 us, 3,6 sy, 0,0 ni, 88,3 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8034,9 free, 4116,4 used, 4876,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 70,0 0,9 58:35.04 deCONZ
top - 21:15:46 up 4:03, 2 users, load average: 1,24, 1,10, 1,04
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 5,2 us, 0,9 sy, 0,1 ni, 93,8 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8034,7 free, 4116,6 used, 4876,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 4,0 0,9 58:35.16 deCONZ
top - 21:15:49 up 4:03, 2 users, load average: 1,14, 1,08, 1,03
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 5,5 us, 0,8 sy, 0,2 ni, 93,3 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8034,7 free, 4116,6 used, 4876,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 3,0 0,9 58:35.25 deCONZ
top - 21:15:52 up 4:03, 2 users, load average: 1,14, 1,08, 1,03
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 8,0 us, 3,2 sy, 0,1 ni, 88,6 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8034,5 free, 4116,9 used, 4876,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11749,9 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 61,0 0,9 58:37.08 deCONZ
top - 21:15:55 up 4:03, 2 users, load average: 1,13, 1,08, 1,03
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,0 us, 4,4 sy, 0,0 ni, 85,5 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8034,5 free, 4116,8 used, 4876,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11749,9 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 99,7 0,9 58:40.07 deCONZ
top - 21:15:58 up 4:03, 2 users, load average: 1,20, 1,09, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,0 us, 4,1 sy, 0,0 ni, 85,8 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8034,5 free, 4116,7 used, 4876,8 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11750,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,0 0,9 58:43.08 deCONZ
top - 21:16:01 up 4:03, 2 users, load average: 1,20, 1,09, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,3 us, 5,0 sy, 0,4 ni, 84,1 id, 0,1 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8007,2 free, 4141,1 used, 4879,8 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11725,7 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 101,0 0,9 58:46.11 deCONZ
top - 21:16:04 up 4:03, 2 users, load average: 1,18, 1,09, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,4 us, 4,3 sy, 0,0 ni, 86,2 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8013,7 free, 4134,6 used, 4879,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11732,2 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 96,0 0,9 58:48.99 deCONZ
top - 21:16:07 up 4:03, 2 users, load average: 1,18, 1,09, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,8 us, 4,5 sy, 0,1 ni, 85,4 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8015,9 free, 4132,4 used, 4879,7 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11734,3 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,3 0,9 58:52.01 deCONZ
top - 21:16:10 up 4:03, 2 users, load average: 1,17, 1,09, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,6 us, 4,3 sy, 0,0 ni, 86,1 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8023,1 free, 4125,2 used, 4879,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11741,5 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 58:55.03 deCONZ
top - 21:16:13 up 4:03, 2 users, load average: 1,23, 1,11, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,4 us, 4,4 sy, 0,0 ni, 86,0 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8026,9 free, 4121,4 used, 4879,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11745,3 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 58:58.05 deCONZ
top - 21:16:16 up 4:03, 2 users, load average: 1,23, 1,11, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,4 us, 3,9 sy, 0,0 ni, 85,7 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8026,9 free, 4121,4 used, 4879,6 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11745,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 101,0 0,9 59:01.08 deCONZ
top - 21:16:19 up 4:03, 2 users, load average: 1,22, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,7 us, 4,9 sy, 0,0 ni, 85,3 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8027,2 free, 4120,9 used, 4879,8 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11745,9 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,0 0,9 59:04.09 deCONZ
top - 21:16:22 up 4:03, 2 users, load average: 1,22, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,9 us, 4,6 sy, 0,0 ni, 85,4 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 8027,5 free, 4120,7 used, 4879,9 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11746,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 59:07.11 deCONZ
top - 21:16:25 up 4:03, 2 users, load average: 1,20, 1,10, 1,04
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 9,8 us, 4,2 sy, 0,0 ni, 85,9 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8027,5 free, 4120,6 used, 4879,9 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11746,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 98,3 0,9 59:10.06 deCONZ
top - 21:16:28 up 4:03, 2 users, load average: 1,26, 1,12, 1,05
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 10,1 us, 4,7 sy, 0,0 ni, 85,0 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8027,2 free, 4120,9 used, 4880,0 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11745,9 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,7 0,9 59:13.08 deCONZ
top - 21:16:31 up 4:03, 2 users, load average: 1,26, 1,12, 1,05
Tasks: 1 total, 1 running, 0 sleeping, 0 stopped, 0 zombie
%CPU(s): 13,6 us, 6,6 sy, 0,3 ni, 79,3 id, 0,2 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Spch: 15866,8 total, 7994,6 free, 4150,7 used, 4882,9 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11716,1 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 R 100,3 0,9 59:16.09 deCONZ
top - 21:16:34 up 4:03, 2 users, load average: 1,32, 1,13, 1,05
Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie
%CPU(s): 6,3 us, 2,3 sy, 0,1 ni, 91,3 id, 0,0 wa, 0,0 hi, 0,1 si, 0,0 st
MiB Spch: 15866,8 total, 8000,9 free, 4144,3 used, 4882,9 buff/cache
MiB Swap: 16251,0 total, 16251,0 free, 0,0 used. 11722,4 avail Spch
PID USER PR NI VIRT RES SHR S %CPU %MEM ZEIT+ BEFEHL
11397 nuc 20 0 1038260 139472 70392 S 36,2 0,9 59:17.18 deCONZ