If you hold the Wi-Fi button for 30 seconds then a full factory reset will be performed. The success of the factory reset is indicated on the Status LED (it will blink red 5 times). In this case all configuration profiles will be cleared. The reset config button at the bottom of the Settings page on the web interface only resets the currently active configuration profile.
Make sure the modem mode is set to D-STAR when you use the D-STAR transceiver and C4FM (or C4FM Half Deviation) when you use the Yaesu transceiver.
In case you use the Yaesu transceiver make sure the Half Deviation setting is turned off in the radio, and use plain C4FM modem mode on the openSPOT. If there's no such setting in your transceiver's menu, or you can't turn it off, then you have to use C4FM Half Deviation modem mode. In this case, run C4FM Half Deviation AutoCal, or manually adjust the RX offset on the Modem page in +-100Hz steps from -500Hz to +500Hz for the lowest BER. You can verify settings using the openSPOT's built-in local echo service.
If AutoCal does not work for you then the RX offset between the transceiver and the openSPOT is greater than 500Hz. What you can do is to switch frequencies on the openSPOT, but keep the transceiver's frequency. For example, if the transceiver is on 433.900MHz, then test by setting the openSPOT to the following frequencies:
433900500 Hz
433900600 Hz
433900700 Hz
...
433899500 Hz
433899400 Hz
433899300 Hz
...
You can use the built-in local echo service to test your own voice.
If the openSPOT's status LED does not blink green when you press PTT even after adjusting the RX offset, then try setting the deviation DU menu to 177, the default value is 150.
If you use a Yaesu FT-70D, then try changing setting #62 Transmit Modulation Level to: [WIDE] and use plain C4FM modem mode. AutoCal is not needed in this case.