I just installed a new Synology RT2600ac router a couple of days ago. In setting it up, I came to Network Center \ Local Network \ DHCP clients. At first, there was nothing there; none of my network devices. I left it over night and the list had a number of devices but not all of them. Conspicuous by its absence was my Synology DS920+. And in a number of cases, the Host Name was either not showing or some sort of device ID rather than the more common name that we are sometimes able to assign. I did a lot of googling and found on the community.Synology forum that quite a number of people were having the same problem. That thread was started in January 2020 with no solution in sight. A ticket was opened with Synology but they were pretty useless.
On perhaps a related problem, earlier this year, I had a problem with my smart TV where devices, like my DS920+ and my QNAP NAS were not showing up. I found out that with an update to my old Asus router, the problem seem to have been created. Long story short, I found that if I turned on the Multicast feature in the Asus router, the missing devices reappeared on the smart TV.
So, last night, I started to poke around my new Synology router. Also in the Network Center is a setting for IGMP Snooping. I recalled that this may be related to the Multicasting setting that cured my last problem. I turned that on ( default is disabled ) and my missing devices suddenly appeared in the DHCP Clients list. I left it sit for a while and my session timed out. When I logged back in to the router, the devices were missing again. Next, I thought that I would turn UPnP back on ( I had previously disabled this as is common. UPnP is Enabled by default IIRC.) as my understanding is that this is used to get devices. As soon as I Enabled UPnP, my missing devices reappeared. I have logged out and back into the router and the devices are still there.
If anyone is also having this problem, this may not be the final answer, but it may get you pointed in the right direction. Maybe enough to at least get your DHCP reservations established.
This is the other forum's thread :
Synology forum thread on missing DHCP Clients
On perhaps a related problem, earlier this year, I had a problem with my smart TV where devices, like my DS920+ and my QNAP NAS were not showing up. I found out that with an update to my old Asus router, the problem seem to have been created. Long story short, I found that if I turned on the Multicast feature in the Asus router, the missing devices reappeared on the smart TV.
So, last night, I started to poke around my new Synology router. Also in the Network Center is a setting for IGMP Snooping. I recalled that this may be related to the Multicasting setting that cured my last problem. I turned that on ( default is disabled ) and my missing devices suddenly appeared in the DHCP Clients list. I left it sit for a while and my session timed out. When I logged back in to the router, the devices were missing again. Next, I thought that I would turn UPnP back on ( I had previously disabled this as is common. UPnP is Enabled by default IIRC.) as my understanding is that this is used to get devices. As soon as I Enabled UPnP, my missing devices reappeared. I have logged out and back into the router and the devices are still there.
If anyone is also having this problem, this may not be the final answer, but it may get you pointed in the right direction. Maybe enough to at least get your DHCP reservations established.
This is the other forum's thread :
Synology forum thread on missing DHCP Clients
