after upgrade to 25.1: strange internet browsing issue [solved by patch 83975b5]

[notspam]

Start from 24.7.12_4.
Before all updates without any issues.
Then upgrade to 25.1 final release by webinterface.
After the upgrade to 25.1 I have strange internet browsing issues.
Traceroute and dns resolution work from client.
If I want open a website the site could not be loaded - it ends with message timeout in browser.
If the website is already open in the browser with an other gateway (f.e. by mobile internet router or by bypassing opnsense) i can then open the links in the same website with browser and opnsense as gateway.

No issues before upgrade to 25.1.

I attached the full upgrade.log.
Anyone with an idea how to find the root cause for this false behaviour ?
Thanks for debugging help.

[terrik]

same beviour on my site. Websites on Linux clients not reachable, sites on windows clients is working fine.
dns, trace, and ping without problem on linux. no proxy in use. IDS/IPS disabled.
https, ssh outgoing not working from linux client, from windows client without problems.
Same network, same DHCP. Before upgrade no problems.
Upgrade from 24.7.12_4 to 25.1

[notspam]

Thx so much for your interesting information.
I hope the community could help us debugging the issue for finding the solution.

[terrik]

Solved. On my site it was modified behaviour with MTU size.

[RayonRa]

Solved. On my site it was modified behaviour with MTU size.

Hi,
https://forum.opnsense.org/index.php?topic=45481.msg227423#msg227423
Issue opened: https://github.com/opnsense/core/issues/8270

[notspam]

Update:
i can confirm too
- the issue is with Linux/Android
- but there is no issue with Windows 10 client

[notspam]

My issue is gone by patching 83975b5.
The opnsense team should build a 25.1_1 release with this patch for avoiding others have the issue after the upgrade to 25.1.

https://github.com/opnsense/src/issues/235

# opnsense-patch 83975b5
# /usr/local/etc/rc.filter_configure

happy now, thanks all for their help finding the right workaround