I have tried to connect my Roku app to my Roku TV a few times, and at first the app just couldn't find my TV. So I tried manually adding the TV with the IP address. Even with being on the same wifi and putting in the IP address it still wouldn't connect. I forgot about it for a while, and tried to connect again today. My TV was on and I had Hulu on in the background, the app found my tv but said it was off. I tried to connect and it said "waking tv up" and then told me it could not connect and to turn on my TV and try again. I tried 3 times, turning my TV off and on again, it wouldn't work. I tried to connect with the IP address again, and my phone had the IP address 3/4 auto populated and wanted me to finish it. However part of what was auto populated was wrong. I tried easing it and typing the correct IP address in and it again told me it could not wake up my device and I needed to turn it on. The TV was on the whole time, and I can't figure out how to connect the app to my TV.
Are you sure you have the officially supported Roku app?
Remove it and reinstall it on your phone making sure its the Official App.
Is it IOS or Android?
Have the TV on and streaming something on Roku.
What type of wifi router do you have? That also feeds the Roku?
Is your remote working fine?
I've had a very similar problem where the app often won't connect to the Roku streaming stick. I have to reboot my modem / router to get it to work. Using an iPhone X and the official roku app.
I have a TCl Roku TV. When I tried to connect my Android Roku app to the TV it would not come up in devices page. I tried manually entering the IP address. Updating the Roku. Making sure that the network was public. Tried resetting the connection. I tried resetting the TV. And followed just about every avenue that the online troubleshooting pages could offer and still no luck. I also have a standalone Roku that I was able to get connected so I'm positive it's not an issue with the Wi-Fi or router settings. On top of this it is impossible to get someone on the phone and truly get down to the bottom of this.
I've had the same problem. Sometimes my RokuTV shows up on the app, sometimes not. My other Roku device shows up every time.
All my devices are on the same subnet, network, router, etc. Actually the Roku device that does work is older on the 2.4 Ghz and I see that all the time. My other devices on the 5G....
Oh, as I wrote this, I think I found the problem. The RokuTV doesn't like the 5G. When I put the RokuTV on the 2.4Ghz it was almost instantly found on the Roku App.
I had to separate the SSIDs on my router so one was for 2.4Ghz, and another was for 5Ghz. With the RokuTV on the 2.4Ghz, it seems to work fine now. My other devices can be on either 2.4 or 5Ghz.
Might suck as this is a 4k TV and doubt it can get 4k over the 2.4Ghz.
One more thing that I think helped was to disable ASUS "airtime fairness". It seems to disconnect lower usage devices randomly.
Thank you! I was about to give up on my app being connected to my TV and unplugging it and aggressively searching for it while it booted seems to have fixed my issues!
The issue crept in again when I merged my 2.4Ghz and 5Ghz wireless bands, causing my headphone audio to be choppy.
I separated them again on their own wireless SSIDs, and it's working again.