On RTK Facet, configuring Wifi and NTRIP credentials works smooth through the WebUI / AP mode, and then switching the Configure Mode and accessing it via the WebUI of the local Wifi is also fine.
However, it seems that Wifi is only used for configuring, and not for connecting to a remote NTRIP Caster to retrieve correction data?
Firmware is factory shipped 3.6
I just tried to reproduce this issue with the Facet and succeeded using firmware v3.9.
On playing around with a few settings, I was able to resolve it by changing the default email (test@test.com) to my actual email address. RTK2Go requires a functional email in case your device causes an issue with the SNIP Caster, so they can contact you and resolve it. After changing the email to a functional one, I was able to receive RTCM corrections over Wi-Fi from rtk2go.com.
On the Config Menu
GNSS Configuration → Enable NTRIP Client → Caster User → your@emailaddress.com
I did notice that, once I was getting corrections over Wi-Fi, and the Facet Configure Mode was still set to Wi-Fi (as opposed to AP mode), I had trouble getting it to connect to my router to configure it again (used a USB serial connection instead).
Can you try this fix, let me know if that solves it for you?
Thank you. I already had set this up with the correct NTRIP credentials for the onocoy https://onocoy.com service, but it still wouldn’t work
After updating to Firmware 3.10, it started working fine. Powering up, connecting to Wifi, then to the onocoy NTRIP caster at clients.onocoy.com:2101 and converging to an RTK fix within seconds using the NRBY_B12 mountpoint 
The way I found to reproduce that issue was with an invalid email, so figured it would be a good starting place; but it ended up just being the firmware version? Now I’m really interested to know why their API was incompatible with our firmware with v3.6, thanks for sharing the source!
I also saw your message about the failed update and was just looking into it when the message disappeared; glad you ended up solving it, flashing problem can be really hard to deal with. Would you mind sharing how you fixed that? It will help the next person to run into an issue like this, and I’m building up a list of user created solutions, so it would help me out too 
Thanks for sharing, and please post again if you run into any more issues.
Indeed it is weird that this did not work with 3.6, but I can’t really imagine why.
On the previous message on firmware update: This was my mistake. I downloaded the firmware in the wrong way from Github, and ended up flashing something other than a proper firmware image. My bad (but also somewhat surprising that the firmware update process doesn’t do any sanity checks on what is programmed, checksums or such). Once I figured out what I did wrong, I removed the post as it was misleading 
Thanks for all the help. We’re using the RTK Faucet in a trade show this week to demonstrated the blockchain-powered onocoy RTK service, hence it was critical to get this resolved.