No new connections after ~15 min after Upgrading to 17.7.4 Firmware

[SiD67]

Hi,

I have upgraded to 17.4 yesterday and have some strange bahavior now.
Upgrade itself was working normal without any errors, exept ids was not strted and I had to reboot.

I use simple nat with 1 wan dsl connection.

After the update it seems like after 15 minutes all _new_ connections going to wan are blocked.

I can ping for e.g. 8.8.8.8 on my pc without any problems, even after 15 minutes when I ping permanently.
But when I try to do simple web surfing after these 15 minutes no connection is possible. Even from the opnsense itself I am not able to ping 8.8.8.8 for e.g.
In the dashboard I can see, that the dsl connection is still up and running. Even the ping from my pc I started directly after rebooting is still working. But any new connections do not work.

When I try to reconnect the wan dsl connectionit will not come up again.

To solve the problems I have to restart the opnsense.

After restart it takes a long time before the dsl connection is up again (20 to 30 tries in log file), but then everything is working again for around 15 minutes.

My hardware is an APU 1 board (realtek cards).

Anyone got an idea what is going wrong?

For me it looks like the firewall is blocking connections after these ~15 minutes, I can´t find any problems in other logs (pppoe, system hardware etc.)

regards,

Dennis