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UniFi OS (Dream Machines) 5.1.15 – safe to update?

Newer release in this line: UniFi OS (Dream Machines) 5.1.33 (2026-09-09). If you're updating now, check that one instead — it may already fix the issues reported here.

Security update: this release fixes security issues. Waiting carries its own risk — if your device is exposed, weigh that against the reports below.

What's in this release

CVEs fixed

No CVEs mapped to this release, though the vendor flags it as a security update.

Community reports

• Problem WAN Instability since 5.1.15 · Reddit · 2026-06-29

  Since my Express 7 was updated to 5.1.15 my WAN connection has dropped once or twice a day. It has continued with 5.1.19. It also has continued after my ISP cleaned the fiber connectors in the slack NID and at the ONT. They also swapped out the ONT. It seems there’s a few other…

• Problem Heat wave + 5.1.15 killed my UDM · Reddit · 2026-06-20

  I've been happily running a UDM for a home network since 2020. For the last year, I've kept it in a small storage cabinet (with an open front) in my living room. Ever since the 5.1.15 release, I noticed CPU usage was on average much higher, and the fan was running more often (Be…

• Mention how to block outbound dns traffic? · Reddit · 2026-07-21

  im running a ucg-fiber(5.1.15) running network 10.4.57, and im trying to block dns traffic from my ring, google, alexa iot devices from using 8.8.8.8 and 1.1.1.1. using the policy engine, i created a firewall rule to block dns traffic out. source zone: iot network: iot service:…

• Mention Having problems with my UDR7 (using SFP for WAN results in certain traffic being slow unless I use any VPN, and routine packet loss) · Reddit · 2026-07-01

  My setup: AT&T Fiber with their BGW320-500 in IP Passthrough to my UDR7, with a TrueNAS server plugged into Port 3 on the UDR7 set at 2.5Gb FDX. That's the simple version at least. Problem 1: SFP WAN weirdness I originally thought it was my ISP throttling my traffic , but now I…

• Mention Slow download speeds connected to UDM Pro Max -Upload perfect · Reddit · 2026-07-01

  I'm at my wits end. I am on the verge of a full factory reset. Here are my speeds directly connected to the Nokia modem through a media converter RJ45-->Fiber https://www.speedtest.net/result/c/92054ca2-db63-4f3e-9c1b-d820c4f27f12 Now if I connect to the UDM Pro Max directly the…

• Mention Cloud Key Gen 2+ Memory usage · Reddit · 2026-06-18

  So i have a UCK Gen2+ which I use for my network controller and I've started to use protect on it as well with just 1 G5 turret camera that records constantly but it seems like the memory is running above 70% and is causing it to disable smart detections which doesn't really hel…

• Mention Unreported periods on my UCG Fiber · Reddit · 2026-06-18

  https://preview.redd.it/gepiyzck808h1.png?width=1980&format=png&auto=webp&s=df56f45ff38b85db303dfb0f39f32f6cad8676ec I'm closely monitoring my statistics since I'm dropping packages in some ocasions, I've activated Adaptive SQM in an external tool to see if I can improve this. W…

• Mention UDM SE has 6 open ports? · Reddit · 2026-06-16

  I did a port scan on my ISP-assigned public IP and it showed the following open ports: 21, 80, 443, 554, 1723, and 8443. I know what the ports are for. However, I haven’t forwarded any of them. My device is also not double NATed so I’m confused as to what this might be. The UDM…

• Mention DNS issues recently · Reddit · 2026-06-16

  Roughly around June 1st of 2026, one of my sites started having DNS errors. Some computers would start losing connection to the network and I wasn't able to ping the UGC Ultra at 192.168.1.1 Restarting the pcs would fix it for a bit but the dns issue would return. I was running…

• Mention Constant Disconnects · Reddit · 2026-06-16

  I have a UDM Pro on 5.1.15. I'm getting constant disconnects. I thought it was a wiring problem so I cut and put new CAT6 Keystones on the cable coming in from my ISP. I've rebooted it several times. It appears its up to date on software. I've spoken to multiple neighbors who al…

• Mention UDM-Pro controller flaps its inform host between two gateway IPs and pins the CPU in a re-provision loop until I hard-reboot. Network 10.4.57 · Reddit · 2026-06-16

  Posting to see if anyone else has hit this, and whether it's known. Setup: UDM-Pro, UniFi OS 5.1.15, Network 10.4.57. Nine adopted devices: four APs and five switches, all wired. Everything sits on a dedicated management VLAN at 10.0.10.0/24. I also still have the built-in defau…

• Mention UDM-Pro controller flaps its inform host between two gateway IPs and pins the CPU in a re-provision loop until I hard-reboot. Network 10.4.57 · Reddit · 2026-06-16

  Posting to see if anyone else has hit this, and whether it's known. Setup: UDM-Pro, UniFi OS 5.1.15, Network 10.4.57. Nine adopted devices: four APs and five switches, all wired. Everything sits on a dedicated management VLAN at 10.0.10.0/24. I also still have the built-in defau…

Reports are found automatically and labelled by an AI model plus keyword rules — they can be wrong. Open the post to judge for yourself.

← UniFi OS (Dream Machines) 5.1.12 · UniFi OS (Dream Machines) 5.1.19 →

Other UniFi OS (Dream Machines) versions

• 5.1.33 2026-09-09
• 5.1.31 2026-08-20
• 5.1.30 Release candidate / early access 2026-08-17
• 5.1.27 Release candidate / early access 2026-08-04
• 5.1.26 2026-07-22
• 5.1.19 2026-06-17
• 5.1.15 2026-06-01
• 5.1.12 2026-05-21