You said in another post you have a Roku TV. But this is not the case. You have 2 Roku Expresses correct? A Roku TV is a TV with the Roku operating system built in. The Roku Expresses you are using only support 2.4GHz WiFI. Please try this.
Here are the settings for 2.4ghz to try (probably won't help in your situation, but worth a shot)
2.4 GHZ BAND
1. Radio is On/Enabled
2. SSID (network name) is On/Broadcasting
3. Network Mode/Protocol is set to b/g/n or b/g/n(Mixed Mode)
4. Bandwidth/Channel Width is set to 20mhz
5. Wireless Channel is set between 1 and 11 (preferably 1, 6 , or 11). Channels 12 and 13 are disabled through Roku Software, so manually setting a Channel will help mitigate issues caused by Auto Setting.