External antenna on a NR5101 router

We just bought a NR5101 to have a better bandwidth than our poor ADSL line, being at 2.5 km from of a mast of our 4G/5G mobile provider with better speed already than the ADSL line with a simple mobile phone. First trials with the integrated antenna resulted in pretty good results in 4G modes at 30 to 110 Mbit/s downloading  and 15 to 30 Mbit/s uploading at different hours of the day. But RSRP, RSRQ and SINR are not stable even on short periods of measurement with SINR between -2 and 14 dB. Furthermore it's impossible to get a 5G link in manual mode (our provider announces 5G NSA service at 700 MHz and 3500 MHz for this station; 4G at 700 MHz is well received in manual mode; 5G is present in full auto mode of the router but with a worse performance than any 4G mode). As we are at 2.5 km from the emitting antennas with no obstacle between the provider's antennas and our home (there is a small valley in the middle) and at almost the same altitude, the solution of adding an external antenna seemed obvious to try. 

We bought and installed outside the house a Halo & Son Coflex 3200 antenna connected to the NR5101 router with the switch in EXT position, and directed toward the visible mast and we made a series of test. The result was very disappointing with no improvement at all vs the internal antennas setup of the router. We suspected a problem with the external antenna and were about to send back the antenna when we decided to make an ultimate test with the antenna disconnected from the router and the switch remaining in EXT position : the result was the same receiving signal we had with both series of tests with internal or external antennas and even a decrease of signal turning 90° left or right the router from the optimum position inside the test room. The hardware switch INT/EXT seems now to be the main suspect (not connected to the board or not working).

Before sending back for an exchange or a refund the router to the dealer, the question is: is this switch only a hardware switch or is there any software possibility to choose the INT or EXT position? Does the switch fall back to internal position (by software) when there is not an external antenna connected?

Accepted Solution

  • pacomano
    pacomano Posts: 7
    Answer ✓
    Last news from Zyxel support.

    The external antenna ports are only for frequencies higher than 3500 MHz, and the internal antennas are used for other frequencies (lower than 3500 MHz e.g. 2600 MHz and below) when external antennas are connected and with the switch on EXT position; when the switch is on INT position, internal antennas are used for all the ranges of frequency.

    When the switch is on EXT position without any external antenna connected, the router works only on 4G/3G/UMTS modes (5G signal could still be received but at a very low level by the external antenna circuit; they made tests: 5G signal with the switch on INT RSRP = -65 dBm, 5G signal with the switch on EXT no external antenna connected RSRP = -90 dBm).

    Zyxel support suspects my Halo & Son antenna is not compatible with the 3500 MHz range (I checked: the manufacturer claims the antenna covers the 3400-3800 MHz range). I rather believe we are too far from the carrier antennas (2.5 km) to be able to receive any signal in this 5G NR NSA mode.

    Although RSRP, RSRQ and SINR are average or bad, as the download and upload performances with 4G are rather good (30 to 100 Mbit/s down, and 10 to 30 Mbit/s up), we will probably keep the router and send back the antenna.

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  • Additionnal info: before the tests we had updated the firmware to V1.00(ABVC.2)C0 and the modem software to RG502QEAAAR11A03M4G version.

    Reading carefully all the posts about the NR5101 router on this forum, we are now 3 people mentionning a problem with the INT/EXT antenna switch.
  • I got Zyxel support at the phone this morning and they sent me a new version of the firmware (V1.00(ABVC.3)C0). I can see the 5G bands now in the WebUI, but I can't connect to any 5G link in practice. The INT/EXT antennas switch issue is not addressed by this new version of the firmware.
  • Pacomano. I have the same problem with the external antennas not working. I live in the countryside with poor mobile coverage so I thought that this new rather expensive router would be the sollution together with an external 5G antenna. But so far I haven't been able to get any result with the antenna. Together with the fact that 5G coverage is bad in the area I will now put the router away and get a stronger Huawei 4G router where I am sure the antenna will work.

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