FAQ
TL;DR: On this A5, speed dropped to 8 Mb/s while others reached 300–500 Mb/s, and it shows "authentication error". Fix by matching WPA2‑PSK, forgetting/rejoining, trying 5 GHz, and testing DNS. This FAQ guides Samsung/UPC users. [Elektroda, blaux, post #17256081]
Why it matters: It helps you quickly resolve home Wi‑Fi login and speed issues without a service visit.
Quick Facts
- Device capability: Galaxy A5 (2017) supports dual‑band Wi‑Fi 802.11 a/b/g/n/ac for 2.4/5 GHz operation. [Samsung Galaxy A5 (2017) - Full phone specifications]
- Router bands: The UPC Connect Box in this case broadcast both 2.4 GHz and 5 GHz networks. [Elektroda, blaux, post #17256793]
- Security mode: Phone and router must use the same WPA2‑PSK setting to connect. [Elektroda, nutergsm, post #17256945]
- Symptom snapshot: Phone showed "authentication error" and only ~8 Mb/s, while others on the same Wi‑Fi hit 300–500 Mb/s. [Elektroda, blaux, post #17256081]
- Tried already: Router reset and factory reset done; the phone connects fine to other Wi‑Fi networks. [Elektroda, blaux, post #17256224]
How do I fix "authentication error" on my Galaxy A5 2017 with a UPC Connect Box?
Do a clean rejoin. 1. On the A5, open Wi‑Fi, tap your home network, then Forget. 2. Toggle Airplane mode on for 10 seconds, then off. 3. Reconnect and enter the correct WPA2‑PSK password. This clears bad credentials and refreshes negotiation. [Elektroda, VooVoo, post #17256278]
Where do I check my Wi‑Fi frequency (2.4 GHz vs 5 GHz) on the Connect Box?
Open the router’s admin panel and go to Wireless settings. You’ll see separate controls for 2.4 GHz and 5 GHz. In this case both bands were enabled. Prefer 5 GHz near the router for higher throughput. [Elektroda, blaux, post #17256793]
What security mode should I use, and does it need to match on the phone?
Use WPA2‑PSK (Personal). The phone’s saved network must match the router’s mode and key. As advised, “WPA-PSK, WPA2-PSK is to be the same as you have set in the router.” Mismatches trigger authentication errors. [Elektroda, nutergsm, post #17256945]
Could invalid DNS cause the connection or speed issues here?
Yes. Misconfigured DNS can cause slow page loads, app timeouts, or failed handshakes. “It looks like invalid DNS.” Test by temporarily setting manual DNS on the phone or router, then retry. If performance improves, keep the new DNS settings. [Elektroda, E8600, post #17256485]
My Galaxy A5 connects to other Wi‑Fi but not my home UPC—what does that indicate?
That points to a router or configuration issue, not a phone hardware fault. Focus on the Connect Box: verify security mode, band, DHCP range, and MAC filtering. Adjust settings and retest. [Elektroda, blaux, post #17256224]
How can I check if MAC filtering is blocking my Galaxy A5?
Log into the router and open Access Control, MAC Filtering, or Blacklist. Ensure your phone’s MAC address isn’t blocked or restricted. Remove it from any deny list, save, and reconnect. [Elektroda, VooVoo, post #17256278]
Why is my A5 only getting 8 Mb/s while others hit 300–500 Mb/s on the same UPC Wi‑Fi?
That gap suggests the phone is on 2.4 GHz or a legacy rate. Ensure 5 GHz is enabled and join that SSID. Avoid guest networks, and reboot phone and router. Update firmware on both, then retest. In this thread, others reached 300–500 Mb/s while the A5 saw ~8 Mb/s. [Elektroda, blaux, post #17256081]
Does WPS help here, or should I avoid it?
Avoid WPS. It is insecure due to known brute‑force flaws and can be unreliable. Disable WPS on the router and connect using WPA2‑PSK with the regular password for better security and stability. [Wi‑Fi Protected Setup (WPS) Vulnerable to Brute-Force Attack]
Where do I find and change DNS on the UPC Connect Box?
Open the router’s admin interface and look under Internet, WAN, or DHCP for DNS settings. If you don’t see them, contact UPC support, or test by setting manual DNS on your phone’s Wi‑Fi connection. [Elektroda, nutergsm, post #17256663]
Could my ISP or router be blocking UDP and breaking apps?
It’s an edge case, but possible. ISP or router‑side UDP restrictions can cause timeouts or very slow performance in apps. If other fixes fail, ask UPC to verify no filtering is applied, or test with another router. [Elektroda, E8600, post #17256881]
What router settings improve phone compatibility and speed?
Use WPA2‑Personal (AES), enable 5 GHz, and set modern channel widths. Avoid WEP and TKIP. These settings improve compatibility and throughput for phones and reduce interference problems. [Recommended settings for Wi‑Fi routers and access points]
How can I force my Galaxy A5 onto 5 GHz to avoid 2.4 GHz congestion?
Temporarily disable 2.4 GHz on the router or give 2.4 and 5 GHz unique SSIDs. Connect the A5 to the 5 GHz SSID, then restore normal settings. This isolates band‑specific issues fast. [Elektroda, nutergsm, post #17256230]
Should I reset software or use warranty if nothing works?
Yes. Try a hard reset or install fresh software on the phone after router checks. If the behavior doesn’t change, use the device warranty or service support. This sequence prevents needless hardware swaps. [Elektroda, nutergsm, post #17256163]
How do I reset network settings on a Samsung Galaxy A5 safely?
On the phone, go to Settings > General management > Reset > Reset network settings. Confirm to clear Wi‑Fi, mobile, and Bluetooth network data. Rejoin your Wi‑Fi afterward. [Reset network settings on your Galaxy phone]
