My phone buzzed on the train home from work: my partner texting to say the kids couldn't watch anything, again. Plex was showing that grey not available outside your network banner in the server settings, and every stream from outside the house had died. I'd fixed this exact thing three times before on other people's setups, and it still took me twenty minutes to remember the order to check things in.
So here is that order, written down properly this time.
The short version: Plex Remote Access is really just one port (usually 32400) making it from the wider internet, through your router, to your NAS. When it says not available, that path is broken somewhere. Our job is to find where.
Understand what "not available" actually means
Plex has a relay server on the internet that constantly checks whether your NAS is reachable from outside. When that check fails, you get the warning. It is not lying to you and it is not a Plex bug, roughly 95 percent of the time.
The failure almost always lives in one of three places: your router isn't forwarding the port, UPnP is turned off or misbehaving, or you have two routers stacked on top of each other (double NAT). We'll rule those out one at a time.
Step 1: Confirm the server is actually running
Before touching the router, open Plex on the NAS itself. On a Synology or QNAP that means logging into the web UI, launching the Plex package, and checking it says running rather than stopped.
Then open Settings, Remote Access in the Plex web app. Note the exact public port it wants to use. The default is 32400, but if you set a manual port earlier you may have picked something like 32410 and forgotten.
Write that number down. You will need it three more times.
Step 2: Try letting Plex do it automatically first
In the Remote Access settings, make sure the manual port box is unchecked, then click Retry. If your router has UPnP enabled, Plex will try to open the port itself and you may be done in thirty seconds.
The first time I hit this, that was the whole fix: UPnP had been switched off during an unrelated router reset. Turn it back on and Plex sorts itself out.
Step 3: Give your NAS a fixed local IP
Port forwarding sends traffic to a specific internal address, like 192.168.1.50. If your NAS gets its IP from the router's DHCP pool, that address can change after a reboot, and then your forwarding rule points at nothing.
Fix this by setting a DHCP reservation in your router (bind the NAS's MAC address to one IP), or by giving the NAS a static IP in its own network settings. I prefer the reservation because you manage everything in one place.
Pick an address outside the automatic range so nothing else grabs it. On most home routers, using something like .50 or .200 is safe.
Step 4: Forward the port manually
Now log into your router and find the port forwarding section. It hides under different names: Virtual Server on many TP-Link and Asus units, Port Forwarding on Netgear, NAT on business gear.
Create a rule that sends the port you noted in Step 1 to your NAS's fixed IP. Both external and internal port should be the same number, and the protocol should be TCP.
| Field | What to enter |
|---|---|
| External port | 32400 |
| Internal port | 32400 |
| Internal IP | Your NAS fixed IP (e.g. 192.168.1.50) |
| Protocol | TCP |
Back in Plex, tick Manually specify public port, enter the same number, and hit Retry. Give it fifteen to thirty seconds. A green tick and "fully accessible outside your network" is what you want.
Step 5: Deal with double NAT
This is the one that catches people. If your internet provider gave you a modem-router combo and you added your own router behind it, you now have two devices doing NAT, and one port forward is not enough.
The symptom: your router's WAN IP starts with 192.168, 10, or 100.64 instead of matching the public address you see at a site like whatismyip. That private WAN address is the tell.
You have two clean fixes. Put the ISP box into bridge mode so your own router handles everything, or set your own router as the DMZ host on the ISP box so all incoming traffic passes through. Bridge mode is tidier long term.
Step 6: When your ISP uses CGNAT
Some providers, especially mobile and newer fibre ones, put many customers behind a single shared public address. This is called carrier-grade NAT, and no amount of port forwarding will punch through it.
You can confirm it the same way as double NAT: a private-looking WAN IP that you cannot change. In the 100.64 to 100.127 range specifically, that is CGNAT almost every time.
Two ways out. Phone your ISP and ask for a genuine public IP (some give one free, some charge a couple of pounds a month), or route Plex through a service like Tailscale or a reverse tunnel so you never rely on incoming ports at all.
Step 7: Don't forget the firewalls
The NAS itself runs a firewall. On Synology, check Control Panel, Security, Firewall and make sure the Plex Media Server rule or port 32400 is allowed. QNAP has a similar setting under its security app.
Some antivirus suites and even the router's own SPI firewall can block the port too. If everything above looks right but Plex still sulks, temporarily disable the NAS firewall, hit Retry, and see if that changes anything. Turn it back on straight after and add a proper rule.
A quick sanity check when nothing works
If you have done all seven steps and Plex still says not available, test the port directly. From a phone on mobile data (not your home wifi), try browsing to your public IP followed by the port, like 203.0.113.5:32400/web.
If that page loads, the network path is fine and the problem is inside Plex, so restart the Plex package on the NAS. If it times out, the block is still in your router or ISP, and you have narrowed it to the network side.
Nine times out of ten by this point, the culprit turns out to be double NAT that someone forgot they'd created by adding a mesh system in router mode. Switch the mesh to access-point mode and the whole thing lights up green.
Getting your evenings back
Remote Access looks intimidating because it touches the router, which most of us treat as a sealed box. But it really is a single port following a single path, and every one of these steps is just checking one link in that chain.
Work through them in order, note your public port, sort your fixed IP, forward it, then rule out double NAT and CGNAT. That sequence has never failed me yet, and it will get the kids back to their shows before the next train home.
Frequently asked questions
Why does Plex say not available when local streaming still works fine?
Local streaming never leaves your home network, so it works even when Remote Access is broken. The 'not available' warning only refers to connections coming from outside, meaning the port from the internet to your NAS is blocked. That is why your home TV plays fine but your phone on mobile data gets nothing.
Do I need UPnP enabled to fix Plex Remote Access?
No. UPnP just lets Plex open the port automatically, which is convenient but a security trade-off. If you keep UPnP off, you can forward the port manually in your router and tick 'manually specify public port' in Plex. Both routes get you the same green result.
How do I know if I have double NAT?
Log into your router and look at its WAN or Internet status page. If the IP shown there starts with 192.168, 10, or 100.64 and does not match your real public IP from a site like whatismyip, you have a second router in front of yours. Bridge mode on the ISP box is the cleanest fix.
Can I use Plex remotely if my ISP uses CGNAT?
Not through port forwarding, because CGNAT shares one public IP across many customers and blocks incoming connections. Your options are to ask your ISP for a real public IP, or route Plex through a service like Tailscale or a reverse tunnel that does not rely on open ports. A WAN IP in the 100.64 to 100.127 range is the giveaway.
What port does Plex use for remote access?
By default it uses TCP port 32400. If you set a manual public port earlier you may have chosen a different number, so always check Settings, Remote Access in the Plex web app for the exact value before creating a forwarding rule.
How long should I wait after retrying before it turns green?
Give it fifteen to thirty seconds after clicking Retry. Plex needs to reach its relay server, confirm the port is open, and update the status. If it is still amber after a minute, something in the path is still blocking it and you should recheck your forwarding rule and firewall.
