Last updated: 24JAN2021
Unless you purchased an RG351P during the first few days it was available, you probably do not have an internal WiFi chip inside your device. This is because they were removed due to speaker noise issues (see my whole post here, which includes a guide to reduce the noise).
But the RG351P has some really great online features, like the ability to download media (box art and videos), download and install new themes, download a cheat database, connect to your PC and load games wirelessly, implement RetroAchievements, and even use an online update tool for the ArkOS operating system. You *can* use an OTG adapter and a USB WiFi module to connect, but it’s a little clunky. So in this guide I’ll show you how some members of the community have installed WiFi chips to their device so they have a seamless experience.
Full disclosure: I have an internal WiFi chip on my device, so I haven’t attempted this myself, but I took copious notes when others were sharing their experience! Note that this is not a beginner’s guide: it includes soldering. If you have any questions or issues with this process, I suggest you post something in the Retro Game Handhelds Discord server (in the #RG351P channel).
Two essential parts of this build are the WiFi adapter and a soldering kit. There are plenty of cheaper WiFi adapters out there (like this one, which I have verified works with the RG351P), but I know for a fact that the TP-Link TL-WN725LN will work with this build, so it’s a safer bet until I hear otherwise.
The TP-Link WN725LN WiFi adapter uses an RTL8188EUS WiFi chip, which is different from the mt7601u chip that was build in the the original internal WiFi RG351P model. While it would make logical sense that any mt7601u chip should work, it appears that using a USB adapter with the mt7601u chip actually DOESN’T work. So at this time I recommend only using the TP-Link TL-WN725LN and its RTL8188EUS WiFi chip, which has guaranteed success.
The soldering kit will include the solder iron, wire (in red and black strings of wire), and the solder itself (in the clear tube with a blue cap); you will need all three of those elements for this project.
The other accessories are optional, but can improve the installation. Kapton tape can be used to prevent short-circuiting the board, and Fun-Tak can elevate the WiFi chip a bit to make it more secure. Finally, you can use some 30 AWG wire to create a WiFi antenna to improve network speeds and reduce signal noise.
Install the WiFi chip
In order to open the back of your device, you will need a hex/torx screwdriver. The sizes vary by unit (usually T5 or T6 screws), so your best bet is to buy a set to make sure you get the right one.
Next, break open the TP-Link WiFi adapter, and extract the chipboard from inside. There’s no glamorous way to do this, just grab some needle-nose pliers and gently take it apart. Thanks to Mateo for the images you see above.
At this point you will want to cut some short pieces of wire from the soldering kit linked above, and solder one end of the wire to a connector on the chip, and the other end to the corresponding connector on the RG351P board. You can see how in the example above they used black wire and soldered each end appropriately (luckily, the connectors line up pretty well). Note that you want this wire to be as short as possible, because the RG351P is low powered (3.3V) and the longer the wire, the more likely you will have voltage drops during heavy WiFi network loads.
I’ve actually never soldered before, so I would recommend you watch a YouTube video or two if this is your first time. It’s what I would do 🙂
Based on advice from users on Discord, if possible you should use kapton tape on the underside of your boards and on top once you’ve soldered the connections. This should prevent the connections from short-circuiting the board. Also, you can put a small amount of funtak to elevate the wifi board slightly off the motherboard. See the image above for an example.
One user was able to greatly improve signal and speed by soldering a 30 AWG wire and extending it to the front right side of the unit. Do note that it does introduce some noise during heavy transfers but not as bad if speaker wires are properly shielded. With this wire soldered to the antenna of the unit, the user went from 65KBs per second max with an average of 19KBs per second to 30KBs per second transfer speed to 512KBs Max with an average of 230KBs per second to 350KBs per second transfer.
Another user used a proper WiFi antenna, like this Airgain N2420 and then placed it in the upper side of the back cover, just above the battery (pictured above). They reported excellent WiFi range since it wasn’t having to deal with any metal shielding.
Finally, you should also shield your right speaker wire with aluminum foil and electrical tape, as demonstrated in this guide. This will greatly reduce signal noise when using your new internal WiFi module. To further reduce signal noise, you could also solder a 0.1uf capacitor to the negative end of the right speaker connector, as demonstrated in this image.
If you’re interested, here is a close-up photo of the original internal WiFi chip. Like I mentioned earlier, using a USB WiFi device that has this chip has NOT been successful. So stick with the TP-Link TL-WN725LN.