The nodule in the middle of your USB power cable is the WiFi circuitry ("Advanced Wireless Receiver“) for your Roku 3810. This is essential for the Roku to connect to the internet via your home WiFi network, and for the remote to communicate with the Roku.
I'd suggest you unplug both ends of this cable, make sure the contacts are clean and undamaged, then fully reinsert into their respective ports.
Also, how are you powering the Roku? If you are powering via a USB port on the TV, many of them do not supply enough power to drive the Roku reliably. Try powering via a USB power adapter plugged into house power. The fine print on the adapter must indicate it outputs at least 1 amp (1000 milliamps).
If the AWR cable proves to be defective, unfortunately replacements are no longer available. The replacement that is available for more recent Streaming Sticks is not compatible with your 3810.
Roku customer service has an answer for everything and take no responsibility for failed software updates, which is 100% the problem. My 3810 worked fine for a year on the current and a very high internet speed. All of a sudden does not want to connect and the remote works about 30% of the time. Roku will tell you to disconnect, restart all the usual BS that never works but the problem is last software update. I have 3 Firesticks, never had 1 single connection issue with them. I am throwing this in the garbage its the last time I will ever purchase a Roku again.
