Networking total failure

I have been using Parallels Desktop for years. I updated to MacOS 11.1 about a week ago. More recently than that, I have encountered a serious neworking problem. Parallels Desktop seems to be involved. I have version 16.1.3-49160.
After launching Parallels Desktop, no network I/O:
imac3 502> ping ****
PING **** (****): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1

After quitting the application, networking is OK again:
imac3 503> ping ****
PING panix2.panix.com (****): 56 data bytes
64 bytes from 166.84.1.2: icmp_seq=0 ttl=232 time=80.029 ms
64 bytes from 166.84.1.2: icmp_seq=1 ttl=232 time=78.121 ms

In both cases, I can reach my router:
imac3 504> ping 192.168.0.1
PING 192.168.0.1 (192.168.0.1): 56 data bytes
64 bytes from 192.168.0.1: icmp_seq=0 ttl=64 time=1.384 ms
64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=0.884 ms
This might be a routing problem.

After launching Parallels Desktop, no network I/O:
imac3 505> netstat -rn
Routing tables

Internet:
Destination Gateway Flags Netif Expire
default 192.168.0.1 UGSc en0
default link#17 UCSI bridge1 !
default link#19 UCSI bridge1 !
10.37.129/24 link#19 UC bridge1 !
10.211.55/24 link#17 UC bridge1 !
127 127.0.0.1 UCS lo0
127.0.0.1 127.0.0.1 UH lo0
169.254 link#4 UCS en0 !
192.168.0 link#4 UCS en0 !
192.168.0.1/32 link#4 UCS en0 !
192.168.0.1 24:4b:fe:2f:d8:c0 UHLWIir en0 1156
192.168.0.3 f0:18:98:63:ad:af UHLWIi en0 920
192.168.0.140/32 link#4 UCS en0 !
192.168.0.175 12:53:49:93:bd:89 UHLWIi en0 927
224.0.0/4 link#4 UmCS en0 !
224.0.0.251 1:0:5e:0:0:fb UHmLWI en0
255.255.255.255/32 link#4 UCS en0 !

Internet6:
...

After quitting the application, networking is OK again:
Routing tables

Internet:
Destination Gateway Flags Netif Expire
default 192.168.0.1 UGSc en0
127 127.0.0.1 UCS lo0
127.0.0.1 127.0.0.1 UH lo0
169.254 link#4 UCS en0 !
192.168.0 link#4 UCS en0 !
192.168.0.1/32 link#4 UCS en0 !
192.168.0.1 24:4b:fe:2f:d8:c0 UHLWIir en0 1191
192.168.0.3 f0:18:98:63:ad:af UHLWIi en0 903
192.168.0.140/32 link#4 UCS en0 !
192.168.0.175 12:53:49:93:bd:89 UHLWIi en0 910
224.0.0/4 link#4 UmCS en0 !
224.0.0.251 1:0:5e:0:0:fb UHmLWI en0
255.255.255.255/32 link#4 UCS en0 !

Internet6:
...

My main issue is, of course, getting my network back. As well, I would
like to try deleting the routes that appear in the table during
failure mode, such as
default link#17 UCSI bridge1 !

I would like to stress that in none of these tests did I launch any Parallels virtual machines. All I did was launch the Parallels Desktop application.

Any suggestions?