Guest Casting onto Neighboring Rooms? All-Optical Networks Block DLNA Broadcast Interference at the Network Layer

In June 2026, Ms. Li from Shanghai checked into a business travel hotel with her child. While a program was playing on the guest room TV, the screen suddenly switched to explicit content, frightening her child into tears. Ms. Li immediately turned off the TV and called the police. Subsequent investigation confirmed that a guest in the adjacent room mistakenly cast private videos to the TV in Ms. Li’s room. The hotel involved then suspended all screen casting services.

This is not an isolated incident. Cross-room casting accidents have repeatedly occurred in Shaoxing, Zhejiang, Shanghai and other regions. One netizen staying at a smart homestay in the early hours found indecent videos automatically playing on the TV, which “could not be exited even with the remote control”. Hotels face refunds, compensation claims, negative reviews and public backlash. Screen casting, a feature originally designed to improve guest experience, has become the top source of guest complaints for hotels.

I. Why Does Screen Casting Keep Landing on the Wrong Room?

The root cause boils down to two words: shared network.
A hotel network technician explained that TV casting requires guests’ mobile phones and in-room TVs to connect to the same network. However, some hotels connect TVs across all guest rooms to the hotel’s public Wi-Fi, or share a single Wi-Fi password among all rooms.

All guest rooms reside on the same local area network, and all devices can “see” one another. Hotel TVs often use generic names such as “Room TV” or “Hisense TV”. Guests browsing casting targets on their phones are presented with a long list of similarly named devices. When a guest in one room attempts to cast to their own TV, they may accidentally select the wrong device, sending their video feed to the television in another room.

A deeper cause lies in the inherent design of casting protocols. DLNA relies on the SSDP multicast protocol to broadcast and discover devices within the same network segment, while AirPlay uses mDNS multicast. When all guest rooms share a single broadcast domain, a multicast query sent by a phone in Room A will trigger responses from every TV on the entire floor.

Traditional hotel Wi-Fi adopts a single LAN architecture. TVs and casting devices across all guest rooms and public areas share the same network segment without per-room VLAN isolation. After enabling casting on their phones, guests can automatically detect TVs from every room in the hotel. Wrong-room casting caused by misselection is not merely the guest’s careless mistake; it stems from network architecture lacking room boundaries.

II. The Three-Way Dilemma of Hotel Screen Casting

Three mainstream industry approaches each carry drawbacks:

1. Enable full-network multicast for casting usability: Casting works smoothly, yet the hotel bears operational risks of cross-room leakage. With all rooms in one broadcast domain, unintended cross-room casting is hard to prevent.
2. Deploy VLAN isolation for guest rooms: Network security is secured, yet native Apple AirPlay stops working. AirPlay depends on mDNS multicast which cannot traverse network segments. Once VLAN segmentation is applied, iPhone users lose casting capability, still leading to complaints and poor reviews.
3. TV-hosted Wi-Fi hotspots: TVs broadcast independent hotspots for mobile connection. This bypasses VLAN restrictions, but creates blind spots for real-name internet authentication for guests, and TV Wi-Fi signal quality remains unstable.

Most hotels struggle to balance these three options, lacking a complete solution that guarantees both security and user experience.

III. All-Optical Network Casting Reflector: Block Broadcast Interference at the Network Layer

AINOPOL adopts a dual-layer strategy: VLANs split broadcast domains at the infrastructure layer, while the casting reflector establishes cross-segment casting links at the application layer. Combined, this architecture fundamentally eliminates cross-room mis-casting.

Step 1: One independent network per room to split broadcast domains
Within the all-optical network architecture, the TV, AP and smart terminals in each guest room are assigned to separate VLANs. Devices from different rooms remain invisible to each other. When a guest’s phone scans casting devices, it can only detect screens within its own room. DLNA SSDP multicast traffic is confined to the broadcast domain of a single room and cannot cross VLAN boundaries.

Step 2: Casting reflector — cross-VLAN connectivity without opening up isolation
With one network per room deployed, how do Apple users cast content? AirPlay’s mDNS does not traverse network segments by default, so iPhones cannot locate TVs inside isolated VLANs.

AINOPOL’s casting reflector solves this challenge. Deployed inside the gateway, it captures and responds to cross-segment discovery packets while preserving VLAN isolation. When a TV advertises itself on the TV network, the reflector captures the packet, rewrites addresses and replies to the guest’s mobile device on the guest network. It does not open VLAN boundaries or allow raw multicast traffic, yet the casting connection can still be established.

The reflector proxies multiple protocols including mDNS, SSDP, DLNA, LeBo and AirPlay. Apple and Android devices support plug-and-play casting. No client software or network reconfiguration is required on sender or display devices. Existing gateways and switches do not need modification, making deployment viable for both new and legacy hotels.

Step 3: One-time QR code per screen for in-person authentication
An additional application-layer authentication sits on top of the reflector. A unique dynamic verification QR code is generated for every casting session on each screen. After scanning the code, the guest creates a one-to-one binding between their mobile phone and the TV in their current room. Device filtering is enforced based on room binding, restricting casting only between paired devices while retaining the guest room VLAN security policy.

Cross-room casting incidents reveal a deeper flaw in hotel network construction. When guest privacy and operational risks are intertwined, simply disabling features only hides the problem rather than solving it. Hotels do not need fewer functions; they need robust underlying network infrastructure so every room is inherently isolated, and casting can be enabled and managed securely.

One network per room blocks cross-room device discovery at the network layer; the casting reflector enables cross-VLAN casting; the one-screen-one-code mechanism locks each casting session at application level. With solid infrastructure, future smart services including casting, room automation and voice assistants can be rolled out without introducing new security risks.

FAQ

Q: What is the most common cause of cross-room casting?
A: Hotel guest rooms share the same local area network. Casting protocols discover devices without identifying room boundaries. A phone in Room A can detect the TV in Room B, caused by the absence of per-room isolation at the network layer.

Q: How exactly is “one network per room” implemented?
A: In the all-optical network architecture, VLANs separate the TV, AP and smart terminals of each guest room into independent network segments. Devices from different rooms cannot detect each other.

Q: Which casting protocols does the casting reflector support?
A: It supports multiple protocols including mDNS, SSDP, DLNA, LeBo and AirPlay, compatible with both Apple and Android devices.