Raymarine RAY63 Installation And Operation Instruction Manual page 51

For reliable wireless performance the signal strength should be better than –75dBm, the closer
the signal is to zero the better the wireless performance will be (e.g. –40dBm is better than
–75dBm).
9. If the wireless channel your hub is using is congested with wireless signals then change your
hub's wireless channel (Menu > Set-up > Wireless set-up > Wireless hub set-up > Wi-Fi channel),
and select a different wireless channel.
Try channels 1, 6 and 11 first as these are usually the preferred wireless channels. Otherwise
try the channel that has the least congestion.
10. If you have a very weak or intermittent signal then you will need to investigate further, please
refer to the wireless location requirements to help establish what may be causing the problem.
11. Repeat steps 6 to 10 with each wireless handset you wish to install.
Location requirements
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