Unfortunately not - I don’t have a Synology myself so can’t do any comparison testing.
I don’t suppose you’re using one of the models mentioned here that are reported to have issues…
Sorry if I missed it but did you try the steps @jetkins posted above? It helped some people that were getting the “connection lost” messages on 2.0.4.5.
This is probably not related, but do you know what version of mono you are running?
No, it’s not listed 
Yes, see below. Other details is listed in the same post.
No - guess i missed that. But, doesn’t work. Or - well, it works if i run it manually:
mono /volume1/@appstore/Duplicati/Duplicati.Server.exe --webservice-interface=*
I edited hostname (added a few, seperated with ; as suggested in the text), saved it, Ctrl+C, checked for other processes, and started the service through the Synology-solution. Same error, once again.
If i run it manually, it’s clear to see that i have the right connection to the backend, cause language is in danish (I’m from Denmark), and not english as is it on the sessions where it’s reporting the error after a few seconds.
I also tried to start manually again, and confirmed that the hostname-value was still defined (and it was).
Whoops - sorry about that. I hadn’t figured out you were posting in both places.
I went ahead and added your DS414 to the list in the other topic and included a link to your issue reported here.
I was hoping you were using the ‘bad’ mono version so we could chalk it up to that, but apparently that’s not the case.
So it works in Danish with a manual run but not English with a through-the-GUI run?
I don’t suppose you could try a manual run in English to see if that also crashes?
Np 
And great.
I could give it a try. Am i able to change that in one of the configs?
I’ve added a few things to the start-script, to get a few more details. But sadly i can’t find any logs.
The following advance options is tried - no 1:
--log-file=/var/packages/Duplicati/logs/log.txt --log-level=profiling
And no 2.:
--log-file=/volume1/@appstore/Duplicati/log/log.txt --log-level=profiling --webservice-interface=*
I can see that the paramters is added to the end of the command - and logging is also working, and ansers is on :8200 :
root 10689 1 0 19:14 ? 00:00:02 mono /volume1/@appstore/Duplicati/Duplicati.Server.exe --log-file=/volume1/@appstore/Duplicati/log/log.txt --log-level=profiling --webservice-interface=*
root 10819 10689 1 19:14 ? 00:00:07 /volume1/@appstore/Mono/usr/local/bin/mono-sgen /volume1/@appstore/Duplicati/Duplicati.Server.exe --log-file=/volume1/@appstore/Duplicati/log/log.txt --log-level=profiling --webservice-interface=*
Here is a fresh log with advance options no. 2, where i just started Duplicati, visited it, waited for the message to show up, and stopped the service:
https://pastebin.com/pLcHwFQd
The same error happens on http://[SYNO-IP]:8200/ngax/index.html, with the advance options.
SO... That means it's time for give the manual run another try, with logging enabled:
mono /volume1/@appstore/Duplicati/Duplicati.Server.exe --log-file=/volume1/@appstore/Duplicati/log/log.txt --log-level=profiling --webservice-interface=*
And… It works just fine, and the Danish GUI shows up:
The only thing found in the log this time, is:
2019-01-09 19:37:24 +01 - [Information-Duplicati.Server.WebServer.Server-ServerListening]: Server has started and is listening on 0.0.0.0, port 8200
EDIT: And more debug…
Tried to tunnel into my NAS on :8200 with --log-level=profiling --webservice-interface=* in use, but it’s still the same error.
If i run it manually it’s working just fine with tunnel to :8200 on the Synology…
I also renew my certifiate, cause… why not? Still same issues in the log.
Regarding Danish vs. English, i don’t think that it’s the reason, cause these details is just based on the language of my browser… And the only reason why it it’s not jumping to Danish on DSM, is cause the connection got lost. I actually think that no connection is transfered between the GUI and the Duplicati backend - or, at least just a bit… But… What do i know 
I
I also changed a few settings, fx. theme and so on, but after loading up through DSM on :5001 it’s back to the default things, so i don’t think that the GUI even connects to the server.
Lastly i have another question… Why is it that the following process keeps running, after i stopped the service in DSM? Is that a bug? (Normally i kill it manually)
root 15102 1 0 19:57 ? 00:00:08 /volume1/@appstore/Mono/usr/local/bin/mono-sgen /volume1/@appstore/Duplicati/Duplicati.Server.exe --log-file=/volume1/@appstore/Duplicati/log/log.txt --log-level=profiling
An earlier post links to the solution, but it came after 2.0.4.5. It’s a tiny edit if you want to do it manually.
Oh, embarrassing. I had my full focus on the other issue. I really hope that someone has a suggestion/fix for this. I’m unsure why there’s even a problem with running it by DSM, now that it works just fine by running it manually through SSH.
Thanks for the information about the hotfix to the script 
Do you have your user added into http group as per step 3) in the INSTALL instructions? User needs to be added even if the user is admin level. After adding my user my connection lost issues disappeared.
Are there any “hard” symptoms of missing that step?
I’m hoping to add an"If X happens check Y" troubleshooting block to the instructions.
No hard symptoms. The install goes through, the web interface initially opens, then shortly after it’s overlayed with “Connection lost …” message.
…
Steps to fix this issue:
- Add current user to the http-group
- Jump out of the window
Another embarrassing recognition. I changed multiple things on my NAS, after going from 4*3TB to a single one, due to all the way to mush space for my personal stuff (Actually started from scratch). I skipped step 3 in the instructions, cause my user used to be in that group… But like everything else, “used too be like…” is not always “as it currently is”.
Hours wasted, and now i’m flying.
TL;DR: Read the damn instructions, and double check if you arn’t 100% sure.
Thanks Brano 
Glad you figured it out! Added this as first item in “troubleshooting” section.
1 Like
Am i the only one experiencing, that i can’t get access to my NAS, however it seems running fine, if i look at the status LED’s. Can’t get access through SSH, NFS, DSM (web) and so on… This started after Duplicati was enabled. I’ll just like to hear if other have seen anything like that before, before i starting check for other issues.
If i use the soft-button to power it down, it’s starting the process, but it keeps blinking like it normally only do for a few secounds. So the only way is to take the power, and bring it back up.
I’ve never experienced that and don’t see how Duplicati could be the cause.
Can you ping your NAS? Have you tried connecting by IP address?
Nope - but check out my quote.
Can’t get access, nope. But it’s just wierd that it showed up after it’s installed. But let’s skip it for now. Will try and see what i can fine. You’re right about it shouldn’t be anything related to Duplicati. Would just like to hear.
Does it respond to ping?
Thank you! - this nearly solved it for me - but only nearly, but lead me the way.
I followed your workaround through multiple times but after point 9 it never worked.
This solved it for me in the end:
- Access DSM via IP: https://192.168.0.11:5001 and start/open Duplicati (it did work that way! Beforehand I only tried by hostname or DNS name…)
- Click on Settings, and enter your Synology’s DNS name, e.g. tower.my.domain in the Hostnames field, then scroll to the bottom of the page and click OK.
(my Synology’s DNS name wasn’t there - besides adding it in step 6… (?!)) - Stop the package from the Package Center
- Check for and kill any server process still running, per Step 2 above.
- Start the package from the Package Center.
Works ever since (besides some other issues: Missing XSRF token AND Cannot restore files from directories containing space in name · Issue #2837 · duplicati/duplicati · GitHub ) - and I’m also on 2.0.4.5 …
Hi everyone,
I’ve installed the latest version of Duplicati (2.0.6.3) natively on my Synology NAS (latest version: DSM 6.2.4-25556 Update 2). However, I still get the same “connection” error as described in this topic…
I’ve done this:
- Stopped Duplicati from Package Center. I’ve checked: no processes related to Duplicati are still running (which is expected, because there was already a fix for this issue).
- Started Duplicati the manual way (via SSH).
- Went to the URL with port 8200 and added my NAS’ hostname to Hostnames (I’ve also tried with * in a later attempt). I can access this URL through IP and hostname.
- Stopped Duplicati.
- Started Duplicati from Package Center.
I’ve also added my DSM user to the DSM group “http”.
When using my IP address to access DSM, it does work (in DSM and through the external URL on port 5001). But it doesn’t work when accessing DSM or the external URL through hostname (not even when using * in the hostnames field of Duplicati’s Settings).
Then I tried naxan’s solution, but when not using the 8002 port URL I don’t get the Hostnames field. You’re right: I don’t see that field in Settings.
Does everything work with a single hostname (because that’s what I’m using)? Or is a FQDN containing dots (.) a necessity?
And do you guys see the Hostnames field in Settings when not using the 8200 port URL?
PS: I’ve also executed this:
sudo su -
/var/packages/Mono/target/usr/local/bin/cert-sync /etc/ssl/certs/ca-certificates.crt
(The CRT file contains my own self-signed certificate.)
Doesn’t work either though… It’s like there is no Hostnames field active when Duplicati is started from Package Center, as I don’t see that field in that case.
Rebooting my NAS doesn’t make any difference…
Thanks!
Pedro
Hi,
Problem is solved. Naxan’s solution was indeed key, but the reason I couldn’t see the Hostnames field was I hadn’t checked “Allow remote access” first. It seems I was just too quick. :-o
So it seems the Hostnames field as set through the 8200 port URL doesn’t count for Duplicati when started through Package Center. Perhaps it depends on the version of DSM, Mono, Duplicati or a combo of them, but at least that seems to be my situation right now (and also naxan’s apparently).
Pedro