SSL VPN web mode strange behaviour, 403 - access denied on login screen.

Hi,

I'm trying to use SSL VPN web mode on a FortiGate 60F running v7.4.8 build2795 (Mature). This has worked before and has stopped working without changing the config. Is anyone else experiencing simular issues?

Thanks

-- Screen when browsing to WebVPN --

First screen after browsing to webvpn

-- Screen after pressing OK --

login screen after pressing 'ok' on first screen

-- Browser network log --browser network log

Fortigate diagnose log:

2025-06-02 11:56:23 [403:root:b]req: / 2025-06-02 11:56:23 [403:root:b]mza: 0x358f360 /rmt_index.html 2025-06-02 11:56:23 [403:root:b]fsv_check_path_passed:997 No access: check path failed /migadmin/rmt_index.html, /data/migadmin,  /migadmin 2025-06-02 11:56:23 [403:root:b]sslvpn_zip_handler:136 sslvpn check path failed. 2025-06-02 11:56:23 [403:root:b]req: /sslvpn/css/ssl_style.css 2025-06-02 11:56:23 [403:root:b]mza: 0x358f3a8 /sslvpn/css/ssl_style.css 2025-06-02 11:56:23 [403:root:b]fsv_check_path_passed:997 No access: check path failed /migadmin/sslvpn/css/ssl_style.css, /data /migadmin/sslvpn/css, /migadmin/sslvpn/css 2025-06-02 11:56:23 [403:root:b]sslvpn_zip_handler:136 sslvpn check path failed.