In Coins v1203 onwards, user sessions will be forced to re-authenticate if the session WAN IP address changes. This results in the user being logged out, potentially multiple times. if the WAN IP address keeps changing.
A new parameter was introduced to help with this - SY/WEBIPS.
The solution is to set SY/WEBIPS to contain a comma-separated list of permitted IP addresses from which users can login. When adding the ip addresses, wildcards are permitted. EG: 1.2.3.*,4.5.6.* would allow login form addresses that begins with 1.2.3 and 4.5.6. A single wildcard (*) in the parameter will allow all addresses, but this is not recommended as it is not secure. The IP address in the parameter might be a VPN subnet, or known remote office addresses for example.