sudo -i

synoservicecfg --list
synoservicecfg --hard-stop <service>
synoservicecfg -stop <service>
synoservicecfg --hard-start <service>
synoservicecfg -start <service>
synoservice –status
synoservice –restart <service>
synoservicectl –restart <service>

Apache webserver:

stop pkg-apache22
start pkg-apache22
reload pkg-apache22

Sonarr/Radarr service:

stop pkgctl-nzbdrone
start pkgctl-nzbdrone
stop pkgctl-radarr
start pkgctl-radarr

restart DSM Webapplication:

restart synoscgi

Uninstall Universal Search:

synopkg uninstall SynoFinder

Synology provides additional tools to diagnose a system. These tools only need to be installed as root. Log in as root or as user and then use sudo su to become root.
To install:

synogear install

Installation takes a little while.

The list of tools can be obtained using the command:

synogear list

All tools:
addr2line	       eu-unstrip	   name2addr	      sadf
addr2name	       file		   ncat		      sar
ar		       fio		   ndisc6	      sh
arping		       fio2gnuplot	   nethogs	      sid2ugid.sh
as		       fio-btrace2fio	   nfsiostat-sysstat  size
ash		       fio-dedupe	   nm		      slabtop
autojump	       fio_generate_plots  nmap		      sockstat
avahi-browse	       fio-genzipf	   nping	      speedtest-cli.py
avahi-publish	       fio_latency2csv.py  nslookup	      strace
avahi-resolve	       fiologparser.py	   objcopy	      strings
bash		       fio-verify-state    objdump	      strip
c++filt		       fix_idmap.sh	   perf-check.py      sysctl
cifsiostat	       free		   pgrep	      sysstat
clockdiff	       gcore		   pidof	      tcpdump_wrapper
dig		       gdb		   pidstat	      tcpspray
domain_test.sh	       gdbserver	   ping		      tcpspray6
elfedit		       genfio		   ping6	      tcptraceroute6
eu-addr2line	       gprof		   pkill	      telnet
eu-ar		       iftop		   pmap		      tload
eu-elfcmp	       iostat		   ps		      tmux
eu-elfcompress	       iotop		   pstree	      top
eu-elflint	       iperf		   pwdx		      tracepath
eu-findtextrel	       iperf3		   ranlib	      traceroute6
eu-make-debug-archive  kill		   rarpd	      tracert6
eu-nm		       killall		   rdisc	      uptime
eu-objdump	       ld		   rdisc6	      vmstat
eu-ranlib	       ld.bfd		   readelf	      w
eu-readelf	       ldd		   rltraceroute6      watch
eu-size		       log-analyzer.sh	   run		      zblacklist
eu-stack	       lsof		   sa1		      zmap
eu-strings	       ltrace		   sa2		      ztee
eu-strip	       mpstat		   sadc

From now on, these commands can be used directly in the command line. In package center this is now listed as “Diagnosis Tool” and can be removed from there. An installation via package center is not possible though.

When trying to ssh into synology, the following error message may be displayed:

Unable to negotiate with x.x.x.x port 22: no matching cipher found. Their offer: aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc

Logging in by specifically using one of the offered ciphers works:

ssh -c aes256-cbc admin@x.x.x.x

This can be changed via the DSM interface:
DSM control panel → Terminal → advanced settings → “high” profile

Alternatively, the sshd_config can be changed from the command line with the desired ciphers:

sudo vi /etc/ssh/sshd_config

and replacing the ciphers aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc with

Ciphers aes128-ctr, aes128-gcm, aes192*, aes256*, dhge-sha256, curve25519-sha256, hmac-sha2-256 

Restart the synology for the changes to take effect.