wlan0 goes down but system doesn't notice

A Pi2 running 
FreeBSD generic 16.0-CURRENT FreeBSD 16.0-CURRENT #5 main-n281932-07e6bfeae5a1: Fri Nov 21 00:43:58 PST 2025     root@generic:/usr/obj/usr/src/arm.armv7/sys/GENERIC arm

seems to be dropping its wifi without noticing. 

It picks up a connection hands off on boot but loses it after a few hours.
Sometimes it reports

Nov 22 17:12:53 generic dhclient[4381]: send_packet: No buffer space availableg: Name could not be resolved at this time (2)

Attempts to ping by name seem to fail silently, ping by number fails with

# ping 192.168.1.254
PING 192.168.1.254 (192.168.1.254): 56 data bytes
^C
--- 192.168.1.254 ping statistics ---
21 packets transmitted, 0 packets received, 100.0% packet loss

Resetting the interface seems to fix the problem without difficulty:

# ifconfig wlan0 down
Nov 22 17:29:23 generic dhclient[4381]: My address (192.168.1.11) was deleted, dhclient exiting
# 
# Nov 22 17:29:26 generic dhclient[4381]: connection closed
Nov 22 17:29:26 generic dhclient[4381]: exiting.

# ifconfig wlan0 up
run0: firmware RT3071 ver. 0.33 loaded
# Nov 22 17:29:58 generic wpa_supplicant[3373]: ioctl[SIOCS80211, op=20, val=0, arg_len=7]: Can't assign requested address
# ping www.zefox.net
PING www.zefox.net (50.1.20.27): 56 data bytes
64 bytes from 50.1.20.27: icmp_seq=0 ttl=63 time=5.868 ms
64 bytes from 50.1.20.27: icmp_seq=1 ttl=63 time=4.630 ms
64 bytes from 50.1.20.27: icmp_seq=3 ttl=63 time=4.892 ms
64 bytes from 50.1.20.27: icmp_seq=4 ttl=63 time=4.890 ms

It isn't surprising the wifi link drops, signal has been poor for 
some time. It's more surprising that the failure isn't noticed and
corrected by the system. Dmesg duly notes my manual resets of wlan0
but reports no other problems.

Any suggestions appreciated. 

Thanks for reading,

bob prohaska