There is already been a thread regarding the connection spikes issue on M5, and it seems the problem is still there. 

My Ping looks like this: 

Request timeout for icmp_seq 185
64 bytes from 192.178.25.174: icmp_seq=186 ttl=118 time=44.880 ms
64 bytes from 192.178.25.174: icmp_seq=187 ttl=118 time=29.801 ms
64 bytes from 192.178.25.174: icmp_seq=188 ttl=118 time=31.107 ms
64 bytes from 192.178.25.174: icmp_seq=189 ttl=118 time=31.076 ms
64 bytes from 192.178.25.174: icmp_seq=190 ttl=118 time=36.173 ms
64 bytes from 192.178.25.174: icmp_seq=191 ttl=118 time=34.516 ms
64 bytes from 192.178.25.174: icmp_seq=192 ttl=118 time=55.367 ms
64 bytes from 192.178.25.174: icmp_seq=193 ttl=118 time=29.934 ms
Request timeout for icmp_seq 194
64 bytes from 192.178.25.174: icmp_seq=195 ttl=118 time=27.019 ms
64 bytes from 192.178.25.174: icmp_seq=196 ttl=118 time=32.849 ms
64 bytes from 192.178.25.174: icmp_seq=197 ttl=118 time=27.941 ms
64 bytes from 192.178.25.174: icmp_seq=198 ttl=118 time=30.040 ms
64 bytes from 192.178.25.174: icmp_seq=199 ttl=118 time=32.744 ms
64 bytes from 192.178.25.174: icmp_seq=200 ttl=118 time=34.578 ms
64 bytes from 192.178.25.174: icmp_seq=201 ttl=118 time=32.495 ms
64 bytes from 192.178.25.174: icmp_seq=202 ttl=118 time=27.896 ms
Request timeout for icmp_seq 203
64 bytes from 192.178.25.174: icmp_seq=204 ttl=118 time=28.050 ms
64 bytes from 192.178.25.174: icmp_seq=205 ttl=118 time=28.246 ms
64 bytes from 192.178.25.174: icmp_seq=206 ttl=118 time=32.898 ms
64 bytes from 192.178.25.174: icmp_seq=207 ttl=118 time=28.415 ms
64 bytes from 192.178.25.174: icmp_seq=208 ttl=118 time=27.284 ms
64 bytes from 192.178.25.174: icmp_seq=209 ttl=118 time=27.769 ms
Request timeout for icmp_seq 210
64 bytes from 192.178.25.174: icmp_seq=211 ttl=118 time=30.940 ms
64 bytes from 192.178.25.174: icmp_seq=212 ttl=118 time=33.785 ms
64 bytes from 192.178.25.174: icmp_seq=213 ttl=118 time=27.796 ms
64 bytes from 192.178.25.174: icmp_seq=214 ttl=118 time=31.698 ms
Request timeout for icmp_seq 215
64 bytes from 192.178.25.174: icmp_seq=216 ttl=118 time=72.752 ms
64 bytes from 192.178.25.174: icmp_seq=217 ttl=118 time=29.881 ms
64 bytes from 192.178.25.174: icmp_seq=218 ttl=118 time=28.147 ms
64 bytes from 192.178.25.174: icmp_seq=219 ttl=118 time=28.911 ms
Request timeout for icmp_seq 220

And ping to Deco:

64 bytes from 192.168.68.1: icmp_seq=978 ttl=64 time=14.062 ms
64 bytes from 192.168.68.1: icmp_seq=979 ttl=64 time=10.980 ms
64 bytes from 192.168.68.1: icmp_seq=980 ttl=64 time=5.516 ms
64 bytes from 192.168.68.1: icmp_seq=981 ttl=64 time=14.017 ms
64 bytes from 192.168.68.1: icmp_seq=982 ttl=64 time=8.505 ms
64 bytes from 192.168.68.1: icmp_seq=983 ttl=64 time=7.072 ms
64 bytes from 192.168.68.1: icmp_seq=984 ttl=64 time=8.257 ms
64 bytes from 192.168.68.1: icmp_seq=985 ttl=64 time=8.581 ms
64 bytes from 192.168.68.1: icmp_seq=986 ttl=64 time=8.316 ms
64 bytes from 192.168.68.1: icmp_seq=987 ttl=64 time=6.144 ms
64 bytes from 192.168.68.1: icmp_seq=988 ttl=64 time=5.970 ms
64 bytes from 192.168.68.1: icmp_seq=989 ttl=64 time=7.478 ms
64 bytes from 192.168.68.1: icmp_seq=990 ttl=64 time=6.167 ms
64 bytes from 192.168.68.1: icmp_seq=991 ttl=64 time=8.529 ms
64 bytes from 192.168.68.1: icmp_seq=992 ttl=64 time=9.650 ms
64 bytes from 192.168.68.1: icmp_seq=993 ttl=64 time=9.088 ms
64 bytes from 192.168.68.1: icmp_seq=994 ttl=64 time=7.276 ms
64 bytes from 192.168.68.1: icmp_seq=995 ttl=64 time=8.626 ms
64 bytes from 192.168.68.1: icmp_seq=996 ttl=64 time=13.080 ms
64 bytes from 192.168.68.1: icmp_seq=997 ttl=64 time=5.393 ms
64 bytes from 192.168.68.1: icmp_seq=998 ttl=64 time=5.580 ms
64 bytes from 192.168.68.1: icmp_seq=999 ttl=64 time=6.936 ms
64 bytes from 192.168.68.1: icmp_seq=1000 ttl=64 time=5.868 ms
64 bytes from 192.168.68.1: icmp_seq=1001 ttl=64 time=10.534 ms 

I have the latest firmware update (1.6.5). Is there any chance to fix it?