I have a few Pi's over here and all devices have the same issue:
When connected to a Wi-Fi network te PI is starting to cause issues with either accessibility from outside (ping, ssh, etc.) and also multicasting (not discovered anymore). This only happens after a while (15 - ... minutes).
Strange though is that when performing pings from the Raspberry itself (connected via HDMI) the connection to the internet is all ok. I can ping any website or internal address without any issues.
When I ping to the internal network address from the Pi (that is trying to access the Pi) it looks like the issue solves itself and the Pi is accessible from outside again ... for a while.
lo no wireless extensions. wlan0 IEEE 802.11 ESSID:"MY_WIFI" Mode:Managed Frequency:2.462 GHz Access Point: 00:11:22:33:44:55 Bit Rate=72.2 Mb/s Tx-Power=31 dBm Retry short limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=64/70 Signal level=-46 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:440 Invalid misc:0 Missed beacon:0 eth0 no wireless extensions.
wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.178.31 netmask 255.255.255.0 broadcast 192.168.178.255 inet6 fe80::ba27:ebff:fec9:941 prefixlen 64 scopeid 0x20<link> ether *********** txqueuelen 1000 (Ethernet) RX packets 22357 bytes 3949874 (3.7 MiB) RX errors 0 dropped 1 overruns 0 frame 0 TX packets 43586 bytes 12945370 (12.3 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
After weeks of trouble shooting I decided to ask the community for help.